It takes 10,000 hours of practice to be a success, writes Malcom Gladwell in Outliers.
Overall, practice explains 12 percent of performance, the study concludes. That varies by the task.
. . . if the context in which the task is performed is very stable (e.g., running) 24% of performance is explained by practice. Unstable contexts (e.g., handling an aviation emergency) push this down to 4% .
The value of practice peaks for games at 26 percent and hits 21 percent for music. It accounts for 4 percent of performance in education, the study concludes, and less than 1 percent in the professions.