Law of 10000 Hours

I went to a concert in Carnegie Hall today to see my 14 year old cousin perform. It was a recital presented by winners of this competition, and the performers ranged from pre-kindergarten children to college students. I especially was mesmerized by the youngest performers, who played complex pieces that were five minutes long (and they memorized it all). This made me remember the discussion of 10000 Hours Law by Malcolm Gladwell in one of my Communicating Data assignment article. This kid that was barely as tall as the piano chair perfected his artistry, and there is no way he spent 10000 hours practicing (that is 5 hours of practicing everyday for more than five years). This made me feel like the number 10000 was pretty arbitrary, just a number that signifies a "long period of effort".