That depends upon the instructor's approach. If you came to me, I'd make you do it the way I teach while I'm teaching it - because my job is to teach you that method. But in sparring, I don't care, unless you're dodging weak areas (someone from TKD would be required to use their hands, not their kicks). If a student didn't want to do those things early in their training, they aren't really interested in learning what I can teach, so I'm probably not much use to them. Later in their training, I'm far less concerned with whether they use methods I teach or something they learned elsewhere.Edit: I can almost guarantee most traditional styles wont let me fight how i want to fight, eg if i say i want to do vertical punches (which we all know i am fond of now) they will provably be non comprising given it might not be taught to low belts and isnt in Patterns.
Covertly and with pad/sparring i might have more luck as i have done a pad session with vertical punches with little complaint, Instructor either didnt know (more likely) or care.
I will get back to you when i start going again and see how well it goes wanting to the type of punch i want to do. Overtly say i want to do X punch and not Y. Perfectly fine if they complain about my technique though.