I met a pro a few years ago that has a swing technique that is supposed to be back friendly. It seems to defy much of the geometry that we view as very important in TGM, and really in most golf instruction.
The backswing shoulder turn should go no more than 70 degrees. The idea of the plane is different also. The flashlight would point to the line the feet are on, with backswing and downswing. He wants a vertical pick up of the arms on the backswing. He does want a Flat Left Wrist.
At the finish... there is an up move, similar to the Stack and Tilters.
The club obviously does get on plane eventually, or it would not strike the ball.
He has produced numerous good players... including his son D.J. Trahan on the P.G.A. Tour.
This would be a Class "X", but what do you make of this?