If it aint broken, don't fix it. When someone has grooved a stroke that looks a bit wonky, to a high standard, I believe one should be very careful about changing it. Not every player sees a shot the same way, not everyones hand is exactly the same etc...If however the player is being inconsistent, then revisiting and revising the fundamentals is in order. Not everyone can look like Davis, Murphy et al. That's ok, you don't have to be textbook perfect as long as you are consistent. Are you going to change Bustamante's stroke to a textbook snooker stroke? Of course not, and if you are you should be stripped of your coaching credentials!