Any item that takes durability loss (jackhammers, weapons, etc) can be stored in the bank to remove the previously unrepairable portion of the 'health' bar creating the ability for items to be repaired infinitely.  (use item -> repair several times -> place in bank -> remove from bank -> full repair again).

Is there a setting that can be changed to fix this or is this intentional?

Yeah, this is pretty annoying feature in this plugin, ppl need only to get one repairable item and they can endless repair it :( It really doesn't matter for example that exp ammo breaks guns faster since they can repair those just placing them in bank and take out and all damage is gone. Ofc one solution would be to put all repairable items in blacklist, but then i think part of the idea of having this plugin is lost...