One should be making identical setup changes to all cars on a per track basis. the cars have geometry to make them all neutral. if a track has a tight corner you could be compensating with tuning when you just have cornering problems, your looseness going in, you yourself could be making the rest of the corner a problem when in fact it really isn't. As a driver it's very easy to mislead yourself into believing how your car is reacting through a corner. Just let the computer do the work. Only after you have a neutral handling car entering the corner& through the middle do you attempt to work on adjustments.
http://imgs.xkcd.com/comics/duty_calls.png