Guns and ammo do vary but measured accuracy does fall off on precise rifles after a certain number of rounds. 150 or so seems average. Also most like 1-5 fouling shots. I don't know if you can over clean them. But I know for sure you can under clean them.
I agree with the 150 comment. Lots of guns have been damaged by under-cleaning. This is for the majority of shooters, competition is a whole different ballgame.