So, here we are. Two different camps- the don't drops, and the o.k. to drops. Many points have been made on both sides, but it looks like the trees are getting lost for the forest.
So, we have to ask ourselves- why are most instructors advocating not to drop the elbow, when so many good players do? If you stop and think about it for a minute, the answer becomes quite obvious.
What are the instructors doing? They are TEACHING. IMHO, any instructor that would say you can stoke it any way you want to, as long as you are consitent with it, should NOT be an instructor. Because what they are actually saying is -go spend 5 or 10 years to be consistent. They aren't teaching you anything.
We have already seen in this thread how little time the tip is on the cueball. (Although, for some, seeing isn't believing) So what we are left with, is how to accurately and repeatedly get the tip to the cueball in as little training as possible.
We could be like the top players all you have been mentioning, who didn't know about the pendulum stroke, and shoot thousands upon thousands of balls to figure out what works for each person. OR we can re-create in the body what a simple machine to do the task would do. Which, surprise, happens to be the pendulum stroke. Zero elbow movement.
Now, being human, and not machines, can we duplicate this simple movement EVERY time? Not likely. BUT- that is what we should strive for. Depending on our stance at the table--stretched out or not, the elbow may drop a little on some shots. But the less it drops, the less can go wrong with the delivery to that precise spot we are trying to hit.
The less drop, the more repeatable it becomes. The more repeatable, the more accurate. And the less time it takes to learn.
Instructors are not trying to make robots out of everybody. It can't be done. What we ARE trying to do, is show the fastest, most accurate, most repeatable way to become very consistent. Which is at the core of becoming good in this game.
Each person is different. We have all levels of talent on this forum. Are we advocating that Earl S. should change his stroke? Of course not. But take a good long look at Buddy Hall. If you have ever really tried to learn from him (in person, books, or tapes) you will have come away with something very important. -- The clock method. The only way this works is to consistently hit the cueball where you intended to. This requires repeatability. How do you teach repeatability? By the quickest, easiest, way possible. Which just so happens to be the pendulum stroke.
Will the elbow ever drop? Sure it will. But the whole idea is for it not to drop. When you start to get lazy, you will notice your elbow dropping. This is one of the first signs that your mechanics are starting to slip, and you better get them back in line or other problems will soon develop.
This has turned out a lot longer than intended. But I hope you get my point. This thread has been starting to get a little silly- 'but his elbow drops an inch, and he's good'. Start looking for the trees. THEN you will see the forest.