If it was every class, I agree that it would be a waste of class time. The above excersize I do on my own outside of class, among others. It was taught to me some time ago and I continue it even though I'm not with that Sifu anymore. It is good to do this type of excersize with a group of people from time to time for energy reasons. I feel the reason a Coach/ Sifu would have you do this in class is: 1. Not every body will do this on their own, and it is somewhat of an incentive to do so. 2. If you are doing it wrong, or there is room for improvement, he can help you fine tune it properly. As for any kata or bunkai also.