It reeeeeally depends.
My DS10 is musically talented, but due to his ADHD I've held back on music because he didn't have the EF to practice.
He had a regular teacher for 6 weeks. 30 minute lessons. It was usually too much time and he did poorly (behaviorally) in the lessons. The teacher was soooo impressed by him and praised him heavily. He was practicing 3 hours a day for a while. Then he figured out he didn't have to practice and she would still gush just the same so he stopped practicing, maybe 1 hour over a whole week. He surpassed what this teacher was able to teach in 6 weeks.
He's currently taking 45 minute lessons from a university professor who is meticulous, demanding, AND a really nice guy who sees a lot of his childhood self in DS10. 45 minutes is not enough. They run over into my lesson time each week. DS10 is practicing something like 30 minutes on 3 days and 2 hours on another day. He is practicing less and making more progress. It's a better balance.
If it wasn't for limitations of ADHD, DS10 would be in the "serious music student" category. I'd add trumpet lessons with a university professor, as trumpet is his primary instrument, and he'd be taking music classes at the local community college. The EF just isn't there, not enough hours in the day after dealing with his slow processing speed and everything else that needs to be done.
