I was told by a current Leadbetter instructor that they are not required to read the book but it is made available to them.
Might have sounded as if I was coming after Leadbetter. I have neither reason or intent to do that. I have no clue about him, other than that I do not find his instruction videos the least impressing. But if he'd give me a lesson I'd take it!
I only wanted to point out what I though of as an excellent example of "TGM under the hood".
Anyway I've edited the post deleting "Also requires assistants to read it".