One thing no one has touched on here is that often times the experience of your cast plays into how much rehearsal time you need.  I am currently directing Steel Magnolias with a very seasoned group of women.  I don't have to stop and explain basic theatre terms like "upstage" or "downstage" or "cheat out" or  actors not coaching other actors or any of the myriad of things you have to explain or demonstrate when working with a lot of beginning or first time actors like you often get in community theatre. (WOW!  How was that for a run-on sentence)  I have found that rehearsals go so much smoother and we seem to need less of them because precious time is not used for "educating." KWIM?

Never heard of the hour per minute or the hour per page.   And  keeping people at rehearsals from 5 - 8 hours on a regular basis isn't worth it no matter what the result.  It's far too much to ask from peple that have full time jobs.

Look, I like to keep it simple as a director.  My work ethic is fairly blue collar.  8 weeks, factor in the conflicts, let 'em know when to be off book, remember your blocking and lines and don't bump into the furniture.   OK so I've over simplified my description of what I do but you get the idea.