I should hope everyone is doing each new technique far more than twice, anyway, in order to actually learn it. If they simply split the repetitions between the two sides, it doesn't take longer. And it is my experience that students often make different mistakes on each side, so fixing one side often doesn't mean the other side is right. Mistakes that are made only on one side tell me something different than mistakes made on both sides.There's no reason why you can't practice both sides of techniques in your own time during your own personal training outside of class but in class it's just a waste of time to be honest because you won't get through as much stuff each lesson if everyone's basically doing the technique at least twice and then some will get confused and then it'll have to be demonstrated etc just not worth it in class but by all practicing it on your own doesn't hurt