Well, I have had people think that what they were doing was what the teacher was doing. Or they could not see the differences. And in one case, I had a guy tell me he did not want to punch like the teacher.
Maybe I should explain. One night long ago when I was training with Shiraishi, he showed a technique where you slipped the punch coming in and you grabbed the rear hand guarding his face to do a wrist lock. I did the slip as shown, but there was nothing between me and the the guy's face but air. The guy had thrown a punch with his rear hand on his hip! That is so strange as to mention comment. But when I asked him to keep his hand up like the guy had shown, he sniffed that he did not throw punches like that.
Well, everyone in Japan seems to throw punches like that. And if you don't, the teacher will smack you in the face. Or at least the ones I train with. When you stop leaving something open, they stop hitting you. But was I there to smack this guy in the face or do what the teacher was doing?
But far more often I have run across people that don't understand that even the mere angle of the grabbing arm determines what kind of techique is the best to use. And when you point it out, they think you just can't adapt what you are doing. The point is, we have so many things we could do because there are so many different things that can happen. Doing what is not the most approriate instals in us bad habits.