Last year I read a book called "Outliers" by the sociological writer Malcolm Gladwell. The book examines the factors that contribute to extraordinary levels of success. It is a fascinating read (as other Gladwell books generally are too) and one of the factors that he keeps returning to is what he calls the "10,000 hour rule". This says that in order to truly master a particular field you need to have 10,000 hours of experience in it.
The Spectator at war: A Cabinet of fighting men
40 minutes ago