One of the tricks of the very best ballstrikers was to enter 430 approach with what seemed like an alarmingly open clubface and then also exit on the through swing with the clubface still open. It's kind of a magic trick that I introduce to students with the drill 1 and drill 3 combination. Watch as I show the cone drill to explain.
Tighter circles of motion create faster movement. Learn how you can maintain the swing arc better to help create more speed and much greater control
Rotation is a big word in golf instruction- but how do we rotate to create speed and acceleration of the club whilst also maximizing control of the clubface so we hit the ball straight? 
Snapping the left leg straight near impact brings a whole host of issues into not only the swing itself but also can cause injury. John Daly (above) never had to snap or extend his left leg in an effort to create power- such as other long drivers are prone to do. 
Jim Furyk was ridiculed for his golf swing the moment he came out on tour. Funky looking swings can function better than truer looking swings because of opposite force and pressure. Here is what Furk's funky swing does better than anyone else has done over his career.
During the shutdown of the official PGA Tour season several players have brought their thoughts to social media. Luke Donald purchased my e-book and he sheds some light on post impact in this on the lesson tee video.