One aspect of it is that the 5-15 kid has a ton more spare time. And when practicing is able to be more immersed, not bugged down by real life chores and proble

One aspect of it is that the 5-15 kid has a ton more spare time. And when practicing is able to be more immersed, not bugged down by real life chores and problems like the 25-35. Personal history: I started playing guitar around 18 and at ~25 I was way ahead most of my 18-20 year old peers who had started way younger. And I was a jazz snob since like 20. I did learn the basics of piano and reading music when I was around 7 but never played actively, but it might've helped that I didn't start from scratch at 18. But I was immersed once I started - music was literally all I did in my spare time aside from doing drugs. :D I'm now in my 40s and have been learning piano for the past 2 or so years. I think I've been progressing quite fast, but it's easy since I already know what to do, it's just another instrument (the challenge is mainly the hand coordination).