The 10,000-hour-rule seems like more of an observation that people who are really good at things are likely to have spent a lot of time doing them.
My anecdotal observation: The people I know who are masters of things, were very good at those things early on and that encouraged them to practice more and more.
UPDATE: Wow there seems to be a lot of information in previous HN threads such as https://news.ycombinator.com/item?id=7323837 or https://news.ycombinator.com/item?id=8197102 and a response to my question in https://news.ycombinator.com/item?id=8197467
Because he's repudiated the idea that he or any other informed researcher claimed 10,000 hours was some magic number, or that practice alone is a substitute for talent: http://www.newyorker.com/news/sporting-scene/complexity-and-...
It would have been more accurate to say "It will be interesting to see how well a gross mischaracterisation of Gladwell's claim stands up to empirical testing".
That Gladwell later wrote a much, much less popular article for the New Yorker in which he walked back that totally outlandish claim doesn't justify indignation at people remembering what he wrote.
In any discussion about mastery, people who have never read Outliers will attribute Gladwell with the idea of the 10,000 Hour Rule, take it out of context, and argue with it as if it were the main point of the book, or as if it was presented as a hard and fast rule.
http://www.sciencedirect.com/science/article/pii/S0160289613...
From what I remember, the claim is that 10,000 hours of deliberate practice work best when:
1. You get immediate feedback on success and failure
2. The thing you are trying to master has a skill set that can be improved, and that improving that skill is sufficient.
That #2 is tricky -- a counter example is stock picking. We have no evidence that there is a skill that can be learned that will make you better at picking stocks, so 10,000 hours of deliberate practice, even with immediate feedback, won't help.
I think that Dan is following a reasonable deliberate practice plan with experts and that he does get fast feedback. What we don't know is if Golf is something that is primarily/mostly/all skill based. For example, what if there was a physical body type that made you better and Dan didn't have it -- then 10,000 hours might not help.
Also, the point of the 10,000 hours is to train your intuitive mind (System 1, the fast thinker) to be as correct as your deliberate mind would be (System 2, the slow thinker) if you had time and attention. This whole thing is much better for thinking-based activities, like say, programming. I don't remember if the studies looked at physical activities and "muscle-memory".
Caveat: this is all from memory -- read "Thinking, Fast and Slow" if you have interest in this.
His basic strategy:
1. Write insurance: that gives you tons of cash up front. Get good at setting the price right so you can make money on the float (using money in near term, paying it back in the future)
2. Now with all of this cash, invest in things (like utilities) that need big cash investment, but then pay-back forever (basic rent collecting). He likes things with big barriers to entry (moats)
He does not care if his company stock goes up or down, all he cares about is intrinsic value: the cash generated (now and in the future) and time value of money. His benchmark is the S&P 500 -- he wants to beat their intrinsic value.
But, read the letters -- they are awesome: http://www.berkshirehathaway.com/letters/letters.html