If someone was standing directly behind your back at Address (looking at the back of your head, not down the line), it would be the feeling of pointing the clubhead at them at End. That's what got the change.
Another less extreme way to do this is to attempt to keep the butt of the club pointing at the plane line...at the top and even at the end.
Whatever works is what is important.
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Bagger
1-H "Because of questions of all kinds, reams of additional detail must be made available - but separately, and probably endlessly." Homer Kelly
the blue line that you have drawn, is that the turned shoulder plane?
Is the goal to get the shaft, hands, right forearm, and right shoulder all on the the turned shoulder plane at impact?
Yes, that is correct. And the #3 pressure point, the proximal phalanx of the right index finger.
Note the right forearm is a little under the line. Seems to me he's a bit too squared away for impact.