There are many things that contribute to a fast arm swing, and athletic ability is high among them (if not the chief factor). Nevertheless, there are certain things we all can do that will contribute toward the desired result. Your use of the word 'lean' calls to mind one of these, and I will introduce it with two famous (and seemingly contradictory) quotes.
The first will be of great consternation to the 'Sway and Swing' crowd because it comes from no less an authority than the long-hitting Ben Hogan himself. In a quote I have never seen referenced:
"Most pros even tend to list their bodies a little toward the target at address." [Italic emphasis mine.]
-- Ben Hogan Five Lessons (1957) / Page 43
Now, how does this square with another quote, also from the great Hogan:
"At the address there is no straightening of the right elbow. In order that the right arm will be limp and the right elbow down, one must list slightly from the right side. By list I mean that the right shoulder must be dropped and the hips faced slightly to the left." [Italic emphasis mine.]
-- Ben Hogan Power Golf (1946) / Page 21
Two defined 'lists' . . . one left (toward the target) and one right (away from the target), both made by the same man, the same who arguably was the greatest striker in the history of the game.
What gives?
There is no conflict. Hogan's 1957 'list to the left' was with his lower body, namely, his hips (and supported by his knees and feet)
. This leftward hip shift -- with a centered Head -- resulted in a lower spine slightly closer to the target than the upper spine. And this resulted in his 1946 list to the right with his upper body -- specifically his right shoulder. See the 9-iron stance photo, page 27, Power Golf.
Bottom Line:
For maximum Power and Accuracy, you must be on your left side through Impact. The great players -- from Vardon to Woods -- have begun that transition prior to the Hands reaching the Top of the Backstroke.
Thank you very much for your reply. I sure got a lot out of it.
My post lean was actually a typo. I ment learn. You can bet
that I will hit 500 ball tomorrow with your comments in mind
I will certainly work on them.