So I finished Levitin's The World in Six Songs: How the Musical Brain Created Human Nature
"... ten thousand hours of practice is required to achieve the level of mastery associated with being a world-class expert -- in anything. In study after study, of composers, basketball players, fiction writers, ice skaters, concert pianists, chess players, master criminals, and what have you, this number comes up again and again. Ten thousand hours is the equivalent to roughly three hours per day, or twenty hours per week, of practice over ten years."
For some reason I became irrationally irritated by this. Particularly since he mentioned "fiction writers" by profession...along with master criminals. Rather an interesting sensation to be grouped with master criminals.