Potty Training and M&M's

I am now potty training my third son.  We waited a while before we started training him, mainly because my first two sons took almost a year to potty train fully and I just finished with Evan.  Well Elishah is going to be three tomorrow and I wanted him to be potty trained before the end of summer.  As we have done in the past, we potty train with M&Ms.  It starts out with getting an m&m for sitting on the potty, 2 m&ms for going pee in the potty and 3 m&ms for going poo in the potty.  Well my son is a pretty smart cookie.  He has decided that he is going to "try" to go potty almost every five minutes.  I think it has something to do with getting an m&m everytime.  He runs off the potty and goes straight to our m&m container to get his candy.  We have done the M&M system with all 3 boys but I think Elishah has gotten the most of it.  I think it is about time to rethink the system.