One thing I could never quite get my head around was the concept of having a level left wrist at fix. If it is our goal to have impact as a pure hinge action - the further back of low point we go at fix surely the more wristcock there will be as the left arm and shoulder is above plane during the start impact interval until the left shoulder gets also to the inclined plane at followthrough when the power package is fully inline...
Also on a sidenote here with the rotated shoulder turn vs the onplane shoulder turn - The onplane shoulder turn is impossible accept initially in the downstroke as the axis tilts via hip slide - which spins the secondary lever assembly and right arm onplane like a flywheel.
Think about it - if the power package is fully inline at followthrough the left arm is onplane (or marginally parallel) by going to and in a straight line with the shaft (or more specifically longitudinal center of gravity) - if the left arm is onplane - the right shoulder/arm is onplane and lets say for simplicity sake the base of the neck is the center.... how can there be a position at the top to create this without moving the stationary point....
Let me do a demonstration to point this out - put a pen on a table (a plane) and press it in the middle to create a pivot point - now both ends of the pen represent a shoulder - now turn the pen notice that it does not leave the table - now think of a reverse motion from follow through back to the top of the backstroke - think about how the left shoulder could never actually leave the plane if the right never leaves the plane. This obviously doesn't happen in golfers strokes....