There are some rough rules of thumb, but since they're "rough" and "rules of thumb," there are plenty of exceptions. They're mostly useful as guides, rather than absolutes.
There are also some rules of definition, which are less elastic. For instance, "saute" means something fairly specific in terms of how much fat, how hot, how much agitation, etc. By definition, you can't saute in a cold pan, you can't saute in a lot of oil (pan-frying), you can't saute without frequent agitation (that becomes searing) and you can't saute in water instead of oil. Are those rules? I'd say so. You might call it a "procedure," instead. That's fine, as long as we're on the same page.
It's useful to keep healthy senses of humor and humility about all this. There are some very fine cooks who are rigid fundamentalists when it comes to the universal correctness of their rules; and some equally fine cooks who've never met a rule that mattered.
When it comes to helping, I'm all about showing people a technique that works, combinations of techniques and ingredients which harmonize, or a recipe that works -- preferably one that stands alone and works as a springboard for improvisation. My personal cooking follows a similar path with a bit of iconoclasm thrown in.
It's fair to say that it's helpful to learn the rule, the rationale behind it, and develop the skills to make it work -- before breaking it.
BDL
