Useful Mind / did not hold up practise daily →
Did not hold up all 15 findings

The 10,000-hour rule

Is the 10,000 hour rule true? No.

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.

Check it yourself: doi.org/10.1177/0956797614535810

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

Checked and written by Devendra K Jha. Published 2026-09-16. How a grade is decided.

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