High force running up the left arm all the way.
Can't do it at all costs since the left shoulder is above the swing plane.
Yes, the right shoulder has important on-plane functions as described in the book.
But the left shoulder has important power functions - if you let it. OB Left just posted and old Yoda post about it:
This is pretty close to how I aim to use the shoulders through impact. Especially the last paragraph. I try to maximize the drag from the left shoulder through the ball because I've experienced that this provides the best lag pressure and the greatest resistance against decel as ch meets the ball, or even when there is heavy grass before the ball.
The heavier the club feels in my left hand through the ball, the more drag I manage to provide from the left shoulder, the better I seem to hit the ball. So this is high on my list of things to monitor. When I'm producing my best golf it feels very continuous from transition and past impact.
The only exception from how Yoda describes it is that I don't try to keep or drive the left shoulder straight through the ball. I shift down to elbow plane, and use the Right Shoulder and Right Arm and Right Hand to negotiate the offset between the shoulder turn and the sweet spot plane through impact.