That's amazing, but this is only at a high level when one has mastered techniques to express exactly what he wants in his mind through his instrument. He just needs 30 mins to may be go over few tricky sections or hear it out. My 12 year old also practices very little, 30 mins per day, he is playing at a very advanced level, doesn't need much time to pick up difficult pieces. Once he gets those technical sections smooth with many repetitions, everything flies pretty nicely. More thoughts on how to play a piece musically. He tries different ideas, when he performs on stage, he often gets inspired and plays with different phrasing, and always better than when he practiced at home. Also if he gets his "home work " done quickly, more time to play ( with friends ) :)