From DojoWiki

"Elite performers in many diverse domains have been found to practice, on the average, roughly the same amount every day, including weekends." - K. Anders Ericsson of Florida State University

The best people in any field are those who devote the most hours to what the researchers call "deliberate practice." It's activity that's explicitly intended to improve performance, that reaches for objectives just beyond one's level of competence, provides feedback on results, and involves high levels of repetition.

Fortune Magazine, "Secrets of Greatness", October 30., 2006, p94.