There are tons of threads about what to do with a shoes-in-the-dryer drummer with a lot of varying advice about how to work with them, etc.
I tend to be of the mindset that all instrumentalists fundamentally need a lot of practice time on their instruments to get good. That doesn't mean you don't help someone out, but you need to know that what you're stepping into isn't going to be an overnight fix.
But I'm wondering if others have had good experiences with sitting down with a poor or green drummer and talking it through, making recordings, working one-on-one, doing all the things we generally hear about. Have you done this? Did it work out? How long did you invest time in it?
My personal experiences have been mostly disappointing; one drummer I agreed to work with has been coming along over the course of a year; I don't coach her, per se, but I was brought in to provide some stability. She's improved about as much as I'd expect someone who practices a lot to improve in that time. I don't know if my influence has been much help. She does work hard, but I wouldn't expect her to be brilliant at this for a few more years at least.
What about everyone else? I don't want to hear about what you think should happen. I'd like to hear about what did happen when you did some of the things that are commonly suggested.