The 10,000-hour rule

Ten thousand hours of practice makes an expert.

What actually happened

Gladwell's number is not in Ericsson's data, and Ericsson objected to it. Macnamara et al. (2014): practice explains ~26% of variance in games, ~21% in music, ~1% in professions.

What to do instead

Deliberate practice — edge of ability, specific weakness, immediate feedback — is what matters. Hours alone predict very little.

The laws that do this job properly

L·09Practise at the Edge, With FeedbackImprovement comes from working just past your current ability on a specific weakness with immediate correction — not from hours.shaky
F·09Four Hours Is the CeilingNobody sustains more than three to four hours of genuinely hard cognitive work a day. The rest of the day is a different kind of work.solid
F·10Specific and Hard Beats Do Your BestA specific, difficult goal outperforms a vague one or an easy one in nearly every task ever tested.proven

Every law on Useful Mind tells you how strong the evidence behind it is. The ones that failed are kept here rather than quietly deleted, because knowing which advice is wrong saves you as much as knowing which is right.

See the ones that held up