Depends on what teacher you're talking about.
For maths, (I have the same teacher for both 3U and 4U) not really. I don't even do the work he sets, whether it's schoolwork or homework. My maths mark is the result of my own work, not trying to be arrogant.
For chem, somewhat. I've learnt from the only other chem teacher in my school and prefer his method of teaching more than the one I have now. My marks in chem have become less stable once I stopped having classes with the other chem teacher. But eh, I'll just self teach myself.
For phys, definitely. He goes into detail with everything, which I like. I reckon the gradual increase in my phys marks are a reflection of how good at teaching he is. The only prob is prolly that, for one, details kinda put people off phys during prelim, seeing as quite a few dropped from phys during prelim. The other is that my teacher can't control the class, so there's plenty of disruption -.-;
I've recently swapped Eng teachers, so dunno how the current one teaches, altho many say he's good.