Interestingly, he's pretty close to (but still under) the ten year mark for getting mastery that Peter Norvig wrote about in an essay about mastering programming. (http://norvig.com/21-days.html).
(This was before the rule changed to 10,000 hours.) It could be interesting for someone more knowledgable about art to indicate at what point he hit 'mastery' (assuming that has already happened) and to then estimate how many hours it took him to get there.
Maybe compared to your personal skills, but do you really think he is a master painter now? Not to criticize his work in any way, but I was always under the impression mastering a fine art was essentially a life's work.
If you want to be completely pedantic about it, a master craftsmen is simply a person who has created, and successfully defended, a masterpiece (basically the medieval craft/trade-guild equivalent to a, well, Master's thesis.) This happened pretty early in life (you didn't enter a guild in full good standing until you became a master), so an arbitrarily-selected "master" wouldn't be nearly as experienced/talented as the few that come to mind when you think of the term.
Your mastery of language to articulate your point has brought me to a new level of understanding.
My reply to you is "yes." Additionally, I'd like to point out that indeed every hour of deliberate practice does reduce the amount suggested by one hour. Unless you have mastered manipulation of space-time, of course.
The OP mentioned two numbers: 10 years and 10,000 hours.
I think alnayyir is trying to say that deliberate practice can bring down the 10 year number (which I agree with and is why the rule switched from saying 10 years to saying 10,000 hours) and michael_dorfman is interpreting that statement to be referring to the 10,000 hours number.
My point in the OP was to show that by having a large amount of data, this provides a nice example for understanding why the rule was changed. (But for it to be a good example, it would require someone knowledgeable about art to look over his prior works and pinpoint when exactly he became a 'master' (although this may be a hard thing to do) and to then estimate how many hours of practice was spent to get there.)
Comments like these make me feel that this place is turning into Reddit as it becomes more popular. It's sad.
Back on topic, the ten thousand hours is supposed to be deliberate practice to achieve mastery. One good source for this is Malcolm Gladwell's book, Outliers.
He REALLY started improving when he started taking those figure drawing classes... You could noodle away aimlessly for 50 years and still be mediocre. Figure drawing basically forced him to teach himself how to teach himself to draw.
(This was before the rule changed to 10,000 hours.) It could be interesting for someone more knowledgable about art to indicate at what point he hit 'mastery' (assuming that has already happened) and to then estimate how many hours it took him to get there.