At the academy lesson tee we often here that the poor  shot that was just hit by the pupil, was caused by many different things. Either I lifted my head or my left arm was bent or the ball position was'nt quit right. All of these may be true but really have little or no effect on the way the ball has been struck. The golf swing is complex and understanding that it is a complex mechanism is better than being confused by oversimplified myths such as above.