Sounds like your instructor has a case of OCD! The instructor I have now tells us she is a rule breaker and proud of it! Quilting is an art. Beauty is in the eye of the beholder, etc...
Whenever I take a class - no matter if it's quilting or anything else, I listen, take notes, then when class is over, I use what ever works best for me. If I learn just one thing, then the class was worth it.
When I was a kid I had two close relatives that both made quilts. One was related to me through my mother and the other through my father. Thank goodness they did not see each other often because they would tell each other what they were doing wrong with their quilts! WWIII!