I have an interesting observation from my jazz teaching. That leap that happens when a student has done enough work for the "lightbulb" to go on is a great thing. That moment when the realization hits that jazz improvisation is not magic, but can be worked on. I have seen it happen at jam sessions - young players sound noticeably better. When I ask what has happened, they say they are working on playing over chord changes and are feeling better. My students come to a lesson feeling good about the tune we are working on. Lightbulb lit!
Then there are students that understand the process, and run away! : ) They don't want to go down that path, and that's fine. I hope they learn enough to be a fan of the music, if not a player - that's great! Lightbulb in that room intentionally turned off to go into another room! Awesome!
I have run into some players (with great potential) who aren't doing the work, but are coming out to sessions and sitting in. I want to positively encourage them to get better at the music. I care! The lightbulb isn't turned on yet, and the player is feeling their way around in the dark. This one is the tricky one, and diplomacy is crucial!
Wish me luck!