This drill was amazing to give me the feeling of the transition from backswing to downswing to get the club swinging down on plane. The compression and solidness of contact was just like how I used to strike the ball when playing my best golf many years ago, it helps you get more control and predictability over the golf ball.
We all know there is so much conflicting information about this move, but this really works and the Physics backs it up, it works for every club in your bag apart from your Putter :-)
Here is the Head on Wall Drill mentioned in the video, its a detailed video with some 3D analysis of Bryson DeChambeau v's Amateur golfer, I demonstrated the drill at 11min 27sec into the video...
I can remember the exact feeling and swing thought I found over 30 years ago as a very good junior golfer. It was the feeling of pulling the club down in transition, the rest from there was just automatic. Your body will instinctively respond to the arms swinging and rotate out of the way so you dont need to think about it :-)