Clear, you mis-perceive this matter. You've been hangingwith the Bucket too long and the grease has finally gone to your brain.
Allow my Vapid response to help clear things up.
First and Foremost is your misconception about the TSP. It's not a fixed Plane. Its angle varies by Club Length. The Shorter the Club Length, the Steeper the Angle.
OB1: "OK daryl you jerk, then if the TSP angle is different for each club, then what does a Flat Shoulder turn mean?"
Daryl: It simply means any angle flatter than a Rotated shoulder turn.
OB1: "OK daryl, smarty pants, then how does one know how flat to turn your shoulders for any specific club length?"
Daryl: Each Clubs Length changes the angle of the Right Forearm at Address. Then, using Extensor Action Takeaway, your Right Shoulder will be directed to the appropriate height and Location per that angle (Magic of the Right Forearm). Longer Clubs will result in a "Lower Right Shoulder" and Shorter Clubs will raise the Right Shoulder Higher.
So, given a short enough shaft, its possible for a Properly applied Flat Backstroke Shoulder Turn to direct the Right Shoulder to the Same Location as a Rotated Shoulder Turn. But it's still called a TSP if it arrive On Plane by Geometrically aligned forces and not a simple 90 degree shoulder-spine rotation.
Isn't it obvious to everyone that while using the Elbow Plane, that one cannot have an On-Plane Downstroke Shoulder Turn? EVER. Someone let 'Bucket' know.
Dingdong,
Is there more mechanical advantage to having your right shoulder on plane or having the right forearm moving at right angles to the axis of rotation? Pick one and tell me why . . .
I'm not quite sure I ever said that the right shoulder could be on plane with the elbow plane . . . however . . . . you have yet to put up anybody that is a living breathing human being that stays on the TSP . . . I await your submission.