The basis for any "way" of flying, is the POH. Where to put carb heat on or off is an obvious example.
"Crusty" CFI's are not always to blame, but we must remember that there is often more than one way of doing something.
When I fly with someone who has a licence, unless they are doing something dangerous or contrary to the POH, then I won't try and change how they are operating to try and fit how I would do something.
We are there to ensure that they are safe and competent and advise as and where needed. That is the skill, not simply forcing your opinion on someone.
In a school, all the FI's should try and teach the same methods, but not all PPL's respond well to this technique. I personally prefer to see a finished "product"who isn't going to kill themselves and has worked out what is best for them, rather than "Monkey see, Monkey do" without any real thought behind their actions.
A wise and exceedingly crusty CFI once told me " The worst worst sort of students are the one's who do EXACTLY what I tell them. The good ones are those that can translate the crap coming out of my mouth into what I WANT them to do, not what I am telling them."
We need different techniques and different styles of teaching, god forbid we end up with a load of identi-kit PPL's without the wherewithall and experiences to try different things when something out of the ordinary happens.