Your body needs to understand the new exercise, the new task. When studying a new exercise, it needs to be tried only a few times; it shouldn't be repeated over and over again. If it is repeated badly many times, your body will "remember" the inappropriate way of execution. But, if an exercise is repeated only three times, the body won't remember inappropriate execution. The next time, you will better understand the right method, and this will automatically lead to more appropriate execution.