[nevermind]

I have read that the uncompensated, maximum support, stroke includes having the trail shoulder and forearm on the same plane as the shaft at impact, the Turned Shoulder Plane. Only, I can't see how that is possible without having a straight trail arm. Unless you only need the bottom edge of the shoulder to sit on the plane for it to be considered on the Turned Shoulder Plane, maybe that is the answer... From all the pics I've seen where the shaft is on the Turned Shoulder Plane at impact, either the trail shoulder or forearm are not on the TSP.

Comdpa, you've said that the trail shoulder should remain on plane in the Downstroke as long as it needs to. What are the determining factors?