I had the same thing - different instructors with different opinions (and 10 times worse when it came to pitot heat!)
Basically I've come to the conclusion that I use it in the circuit (as per the checklist), near VOR's and VRP's, around airfields, and flash it on and off whenever I see possible conflicting traffic.
Pitot heat, well, I have all sorts of options: always on, always off, only on near cloud, only on cloudy days, only on sunny days, only when ice could be a factor, only below 1000 feet, only above 1000 feet, only when you feel it's necessary, ARGHH!!
Basically I now use it when I'm going near cloud and switch it on on the pre-landing checks if there are conditions conducive to icing.
FF