Easy, as far as it needs to!

Seriously though, until the end of the Follow-Through? Even if that is correct

, I'm still confused
Despite comdpa's valiant attempts, I haven't travelled very far since the beginning of this thread. I'll try to list the questions that I'm stuck on.
1. When does a golfer have a preselected Downstroke Clubshaft Plane, and when don't they?
2. If you shift the clubshaft from plane A to plane B during the Downstroke, which is the preselected Downstroke Clubshaft Plane? Or is there no preselected Downstroke Clubshaft Plane where the clubshaft shifts in the Downstroke.
3. Is the trail shoulder on the Turned shoulder plane at the end of the Backstroke, no matter what type of shoulder turn took place?
4. To be "on" a plane angle, should the shoulder be resting on top of the plane or be bisected by it?
5. If you shift the clubshaft from plane A
(Turned Shoulder Plane) to plane B during Downstroke, if possible, should you also shift the trail shoulder from A to B? In most cases that would be shifting down to the elbow or clubshaft plane, the trail shoulder cannot get down to either, can it?
6. How far into the Downstroke does the trail shoulder need to remain on plane, so that leaving it does not cause problems? Like with the hip slide, I guess the answer is "far enough so that X happens, or doesn't happen"
7. Does the above answer vary from pattern to pattern? Why?
8. Is it safe to say that in 99% of cases the trail shoulder should work down the Turned Shoulder Plane?
9. The book says, maybe indirectly, that having both the trail forearm on the same plane as the clubshaft, and the trail shoulder on the same plane as the hands, provides maximum support and is optimal, doesn't it? If yes, how can you have the trail shoulder, trail forearm and clubshaft (
and therefore the hands) all on the Turned Shoulder Plane
(assuming the answer to Q.5 is "no") at impact, without having a trail arm that is straight or very close to straight? An image would be great.
10. I have a feeling that when the golfer has the clubshaft on the Turned Shoulder Plane in the Downstroke, they are likely to move the trail shoulder off plane earlier than someone with the clubshaft on a flatter plane. Is there any link at all or am I way off base?
Any answers, from anyone, would be very much appreciated.
(no smilies left.. the 4 smilie/image per post limit is very annoying [grrr])