I dont think there is one set "form" or "stance" that works for all the pepole all the time . While some are vary biased in this respect , example , "you have to shoot like Dave Cousins shoots" . You may emulate his form and it may be totaly wrong for you . We are all diferant shapes and sizes , form and style of shooting will vary accordingly . While we would all like to get the results Dave getts , I dont think we can do so by trying to copy his form . Sure there are some common mistakes made , overbowing , and overdrawing on length , which are realy machanical , but effect form . I think underdrawing on length is worst than overdrawing , but alot of times the first thing out of a socalled coaches mouth is , " you need to short'n you draw length to get your form right "