[Martee]

You're very correct that the arm does rotate in both. Deliberately in hitting, finally with clubface getting to plane at top. In swinging, the sweetspot lays an the plane much sooner.

AH!... Grab sunglasses immediately, blinding light...

'Sweetspot lays on Plane.... If there were no rotation, then it would be the hosel that laid on the Plane.....

Okay, I believe that is right.

Now, The steeper the Plane Angle, the less the turn is? If the plane Angle was vertical, no turn.?.

The flatter the Plane Angle, then the more the turn.

This is really wrist/hand rotation and the arms are along for the ride so to speak. Maybe if I am tracking correctly the use of arm rotation is not the best, but maybe wrist rotation is more accurate?