Summarizing Answers to the question; "Why do Pro's use the Elbow Plane in the Downswing".
1. It’s a very common delivery path for your hands
2. It may have to do with not wanting to miss left
3. That’s the shaft position that makes impact feel the most solid
4. The natural plane which occurs just before the right arm straightens is elbow plane
5. That is the plane of most swings that gets results
6. It is also the plane that Brian uses in Building Blocks
7. Because most players are swingers…
8. Because centrifugal force dictates it
9. is the plane where the trail elbow is most connected w/the pivot
10. The elbow plane allows the club to be as close as perpendicular to the angle of the spine
11. Support from the right wedge and 'the bat', the right elbow and the 'magic'.
12. you're FORCED to use the elbow plane if you want to play your best. (because of club fitting)
13. it mostly has to do with not wanting to miss left, "what physics wants you to do,"
14. They are on the Elbow Plane because they all use a shoulder turn takeaway
15. The club tends to want to start up on its OWN plane in the takeaway…(Elbow Plane)
16. the Elbow Plane is normally a "Pivot Controlled Hands" Component, as discussed in 10-6-B and 10-24-F.
17. the Elbow Plane the more – almost totally – subconsciously used.
18. Because it works?
19. 'Cause they grip it more in the Right Hand Fingers than Palm? Elbow has to drop in order for the Right Forearm and Shaft to get in the same plane.
20. Elbow plane allows the golfer to attach the elbow to the right hip on the downswing. The pivot and right hip rotate driving the club through contact
21. the majority of pro's angle of attack (angle line path) makes the "true" elbow plane automatic
22. they return to the Elbow Plane for impact because they began the swing on the Elbow Plane.
23. Because they all rotate the hosel around the sweet-spot
24. By swinging heavy clubs as a kid that didn't know any better.
25. Because they are swingers. And because they achieved trigger delay by float loading.