Bulk tested the math with no issue. Heres the results of a smaller test for easier reading
Run time : 600
Reward interval : 60
Timer interval : 30
Reward amount: 11
Reward multiplier : 1.25
Timer ticked!
Total Playtime : 30
Last reward time : 0
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 60
Last reward time : 0
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 90
Last reward time : 60
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 120
Last reward time : 60
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 150
Last reward time : 120
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 180
Last reward time : 120
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 210
Last reward time : 180
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 240
Last reward time : 180
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 270
Last reward time : 240
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 300
Last reward time : 240
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 330
Last reward time : 300
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 360
Last reward time : 300
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 390
Last reward time : 360
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 420
Last reward time : 360
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 450
Last reward time : 420
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 480
Last reward time : 420
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 510
Last reward time : 480
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 540
Last reward time : 480
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 570
Last reward time : 540
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 600
Last reward time : 540
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
(10:52:01) | [TestPlugin] Killed 2module_car_spawned.entity(10:50:03) | Starting Test
Run time : 600
Reward interval : 60
Timer interval : 30
Reward amount: 11
Reward multiplier : 1.25
Timer ticked!
Total Playtime : 30
Last reward time : 0
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 60
Last reward time : 0
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 90
Last reward time : 60
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 120
Last reward time : 60
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 150
Last reward time : 120
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 180
Last reward time : 120
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 210
Last reward time : 180
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 240
Last reward time : 180
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 270
Last reward time : 240
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 300
Last reward time : 240
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 330
Last reward time : 300
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 360
Last reward time : 300
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 390
Last reward time : 360
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 420
Last reward time : 360
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 450
Last reward time : 420
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 480
Last reward time : 420
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 510
Last reward time : 480
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 540
Last reward time : 480
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Timer ticked!
Total Playtime : 570
Last reward time : 540
Time since last reward : 30
Reward fraction 0.5 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 600
Last reward time : 540
Time since last reward : 60
Reward fraction 1 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1) = 11
Final amount : Reward amount (11) * Reward multiplier (1.25)) : 13.75
Merged postAnother test with odd values
Starting Test
Run time : 851
Reward interval : 47
Timer interval : 30
Reward amount: 11
Reward multiplier : 1.25
Timer ticked!
Total Playtime : 30
Last reward time : 0
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 60
Last reward time : 0
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 90
Last reward time : 60
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 120
Last reward time : 60
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 150
Last reward time : 120
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 180
Last reward time : 120
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 210
Last reward time : 180
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 240
Last reward time : 180
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 270
Last reward time : 240
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 300
Last reward time : 240
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 330
Last reward time : 300
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 360
Last reward time : 300
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 390
Last reward time : 360
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 420
Last reward time : 360
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 450
Last reward time : 420
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 480
Last reward time : 420
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 510
Last reward time : 480
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 540
Last reward time : 480
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 570
Last reward time : 540
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 600
Last reward time : 540
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 630
Last reward time : 600
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 660
Last reward time : 600
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 690
Last reward time : 660
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 720
Last reward time : 660
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 750
Last reward time : 720
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 780
Last reward time : 720
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 810
Last reward time : 780
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.
Timer ticked!
Total Playtime : 840
Last reward time : 780
Time since last reward : 60
Reward fraction 1.27659574468085 is greater than 1. Issue reward
Reward amount : (Config amount 11 * Reward fraction 1.27659574468085) = 14.0425531914894
Final amount : Reward amount (14.0425531914894) * Reward multiplier (1.25)) : 17.76561############
Timer ticked!
Total Playtime : 870
Last reward time : 840
Time since last reward : 30
Reward fraction 0.638297872340426 is less than 1. No reward issued.