[O.B.Left]

If the right shoulder moves down plane then the left shoulder must move up so the shoulders do not always go back and through? They must at some time just move down and up?

Yes , if I understand you correctly.

Though one might think their Shoulders turn on the same plane going back and through .........given any Hip Slide , which will Tilt the Axis of the Shoulders ......... and thereby lower the Right Shoulder (all the while with a steady head)..........the plane of the shoulder turn on the Downswing will become Steeper.

The guys who subscribe to Rotated back and through, given any Hip Slide dont actually achieve a non shifting shoulder turn plane.