I totally agree. You master the technique of practicing. You shouldn't have to spend 10 hours a day and I'd be curious to find out what the average practice time is for a professional whatever in a wind ensemble or something. When you're beginning, granted, you could spend maybe 5 hours on muscle memory and strength but after that it's all repitoir and arrangement. Anymore than 4 hours daily for myself personally would be a waste of time. I average 2.