I am in the US on the west coast. I am a social dancer, in International Style, American Style, and several club style dances. I did go through a medal system. I am not a dance teacher. I do know something about teaching and about running a successful business, though. A medal system is good for giving students a sense of progress. But as long as you have a graduated curriculum, that sense of progress can be established. While it may be what serious dancers look for, dance training is less important than getting paying dancers in through the door repeatedly.