I used to change diapers if there was just a little pee in it. Now I look at the clock first to see if there's a naptime coming up soon, and if so will just change the diaper then. If not, then I consider other variables before breaking out a new diaper.
Neither of our kids had problems with diaper rashes, which would have been a factor in more frequent changes.
Do you change your LO's diaper if there's just a little pee in it?