Say again,
I don't disagree with anything you have said. If we take the original post, it asks, why do we seem to all teach something at odds with the POH. And then the suspected conjecture as to why this maybe.
Yes there are I am sure many instructors out there that may teach only one scenario with carb heat without thought that the stude may not appreciate the limitations of a POH.
But I fail to see why we should not use carb heat on approach because it does'nt say so in the POH. We have to teach the system being used (old fashioned carb etc)....through Tech exam, and instructor input. This generally implies that in pretty much any engine you will every come across that as a rule of thumb, carb heat ON whilst at low power (approach) is a wise thing to do. BUT also to teach the stude that as always, check with the aircraft POH before operating such a device.
We as instructors have to also be realistic and realise that quite often most things we tell our students get lost in the haze. So I find that its best to drum at least some form of discipline into that person so that they have some method that 'should' work in most cases. Balance of risk.
Lets remember, there are cowboys and charletens (spelling?). Cowboys are easy to spot and generally get back on track. The latter pull the wool over your eyes and bugger off into the wild blue yonder of PPL and never listen a word that was advised before.......Manuals? Who needs Manuals? I can fly? ITs a piece of P**S! Maybe just maybe that stupid fellow, will remember, as it was drummed into him, that carb heat (might) be a good idea on approach. He has a higher chance of getting it right than he has of getting it wrong as most types as said favour this technique.
We all, I'm afraid, are not perfect! I can vouch for that.