Now, as Alexandre Dumas said many years ago, "All generalisations are dangerous - even this one", but when you think about it, there must be a ring of truth to this idea. It probably explains why I do not feel expert at anything. When I imagine the things that I feel competent to do, there are probably very few that I have practised for 10,000 hours. This period of time, after all, is the equivalent of 5 years of full time work (assuming that an average working year is of the order of 2000 hours).
On that basis, the traditional four or five years spent doing a trade apprenticeship would get the trainee close to this figure. During that time, the apprentice would have done everything from sweeping the floors and making the tea to at least an awareness of the most difficult aspects of their trade. But even as newly qualified 'skilled men' (or women) they would continue to learn rapidly for the first few years, particularly if they change employer or move to a slightly different role.
All is not lost though! The Pareto rule probably applies, at least approximately. After 20% of the time you probably gain 80% of the skill and the remaining expertise is only gained by very detailed study. At the 80% level you can probably cover most of the ground and can feel pretty competent.
The idea also confirms my views about colleagues who change jobs every two or three years. There is little doubt that careers can be built rapidly in this way, and some are cynical about people who climb the career ladder so quickly in this way. Applying the 10,000 hour rule you might say that it confirms why people can be cynical, because these 'high flyers' never actually become expert at anything. They just became pretty good at each role and before they start to get bored they move on to the next. (Mind you - I have worked with some who seem to jump from job to job just about the time that each new employer realises how hopelessly useless they are! I guess this is embodied in the Peter Principle.)
How many hours have you put in on any of your hobbies or your work? Strangely enough, skeptical and atheistic blogging has become one of my hobbies in the last year and I was trying to work out how many hours I have spent on it. The actual writing, editing and shameless self-publicity via Twitter and Facebook might take half an hour per day, but reading around the subject, listening to the news on radio (or TV), to podcasts and simply noticing every day life around us must take at least twice as much time. In a year I might have clocked up a massive . . . 500 hours . . . perhaps!
On that basis, in another 3 years time I might begin to feel like competent atheist, and in the worst possible case I will live long enough to become a real expert just in time to be proven wrong!
P.S. That was irony