This is an interesting thread. I wish all instructors were as calm and rational as the ones contributing here.
Unfortunately, in my experience, some instructors apparently want things done their way simply because it's their way. I have no problem with there not being a cut and dried answer, so long as I'm given an explanation. For instance, to take an earlier example in New Bloke's post, do you put the carb heat back on short final in case you need the extra power for a go-around? I prefer to, but was once told quite categorically that I shouldn't as "you've got enough to do at that point anyway". No you don't, not if you've got everything set up right anyway. But I can see the argument for the other side. It's the attitude of "I know, you don't, so shut up and do it my way" that I'm objecting to. OK, I'm exaggerating, but only very slightly.
Do you think we could make this thread compulsory reading for all flying instructors?