The best musicians I know don't practice compulsively. They don't lock themselves in a room and practice 10+ hours a day.
Their practice is focused and intentional. And there is a minimum amount of time one needs to spend at their instrument to master it.
The sweet spot seems to be about 3 hours a day. This is the time suggested by Jascha Heifetz. I have also observed this time in others (and myself) as well.
But it is not time alone that makes you great. I routinely saw piano majors at university spend 5+ hours a day practicing but they didn't get better. A lot of their practice time was to log hours and to play concerts for themselves.
What does effective practice feel like?