In this video, we look at how the club-shaft should respond in transition. This isn't as much of a deal-breaker as something like proper sequencing, but is extremely beneficial to both the average and high-level player.

You will rarely find a swing where the shaft of the club points inside of the target-line at left arm parallel in the downswing. Phil Mickelson is one of the few good enough to use this difficult technique. Otherwise, good players "shallow" or "flatten" the shaft in transition before steepening it onto the ball and exiting well left through impact. Check out Ben Hogan, Sergio Garcia, Brooks Koepka, and Jim Furyk for examples of this motion.