Here's a great link (courtesy of Bob Lefsetz) of a lecture by an academic
named Gladwell who illustrates the development of the band Fleetwood Mac. He
uses many examples to support his theory that it takes "10,000 hours" (or
ten years at 4 hrs a day) to get to the "top" level.
http://www.aiga.org/content.cfm/video-gain-2008-gladwell