In 1993, K. Anders Ericsson and colleagues compared violin students at the Music Academy of West Berlin. By age 18, the best group had practiced alone for 7,410 hours, the good group for 5,301, and the least accomplished group for 3,420. In 2019, Brooke Macnamara and Megha Maitra repeated the study with 39 violinists, 13 per group. This time the good group logged more hours (9,844) than the best group (8,224).

That reversal carries the lesson for every player who grinds in the practice room or at the bar table. Hours matter, but they do not decide who wins. What you do inside those hours matters too, and that part is in your hands. By the end of this article you will have a five-step plan for turning your next match night into practice that follows what researchers describe.

The short answer: Practice explains part of why some players beat others, but not most of it. A large meta-analysis found practice accounts for about 18% of the differences in sports performance and 26% in games. The researcher behind the idea, K. Anders Ericsson, argues that practice type matters too: goal-driven, with immediate feedback and repeated revised attempts, not just playing more.

Does more practice make you a better player?

Yes, but less than proponents of the idea claimed. Macnamara, Hambrick, and Oswald pooled 88 studies in Psychological Science in 2014 and found practice explained about 12% of performance differences overall. For games it was about 26%, for music 21%, for sports 18%, for education 4%, and for professions under 1%.

Read those numbers carefully. They describe why people differ from one another, not how much a hard week of drilling will lift your own game. Studies of this kind also compare people who already differ, so they show a link, not proof of cause.

We found no peer-reviewed study of pool alone. Treat the numbers as a guide to how skill works in general, not as a measurement of your league. Macnamara put the finding plainly in the Association for Psychological Science release: deliberate practice is "unquestionably important, but not nearly as important as proponents of the view have claimed."

What else separates strong players from the rest?

Hambrick and colleagues, in Intelligence in 2014, examined chess and music and concluded that practice is not sufficient to explain differences in performance. Other predictors in the research summary include starting age, intelligence, working memory, personality, and genes. Practice is one ingredient, not the whole recipe.

Christian Jarrett's summary for the British Psychological Society reports the numbers. Across six chess studies with more than 1,000 players, practice explained 34% of the variation in ability. Across eight music papers, it explained 30%. In one study, grandmasters had practiced anywhere from 832 to 24,284 hours.

That range is the useful part for a league player. If grandmasters can differ that much in hours, then comparing your total with your teammate's tells you very little. Compare what each of you did with the hours instead.

Did the famous violin study hold up?

Only partly. The 1993 study found a step from least accomplished to best violinists in accumulated practice alone. Macnamara and Maitra's 2019 replication in Royal Society Open Science did not reproduce that pattern: practice alone explained about 26% of performance differences, down from 48%. Among the elite, hours did not separate the best from the good.

The replication's sample was small, 39 violinists at an average age of about 21, so it is one data point, not a verdict. Its weekly numbers were striking all the same. The best group practiced alone 22.69 hours a week, the good group 30.65, and the least accomplished group 9.58. The best group practiced significantly less than the good group (p = 0.024).

Ericsson answered the critique with Kyle Harwell in Frontiers in Psychology in 2019. They argued that the original definition matters. Deliberate practice, in their account, involves individualized training with a qualified teacher, a communicated goal, immediate feedback, and repeated revised attempts that approach the goal.

They also name a weaker kind, which they call naive practice: simply doing domain-relevant activity, such as playing games with friends. A league night where you only play games with friends would fall in that category under this definition, which makes it a thin way to improve even if it is good for the social side of the sport.

The replication authors found that the amount of teacher-designed practice did not explain more of the performance gap than practice alone. Violinists also rated it as less relevant to improving. The dispute is real, and the fair reading is that the definition is still being argued.

Does it matter how you practice, not just how long?

Evidence suggests it can. A 2024 meta-analysis by Czyż, Wójcik, and Solarská in Frontiers in Psychology found that mixing up tasks during practice (random practice) beat repeating one task (blocked practice) on later transfer tests, with a medium effect. The authors also rated study quality as generally weak, so treat it as a lean, not a rule.

The analysis covered 34 studies and 1,421 participants. The pooled effect was 0.55 (95% confidence interval 0.25 to 0.86), and it fell to 0.40 once outliers were removed. In applied settings, as opposed to labs, the effect was smaller and not statistically significant.

The tasks in those studies included golf, volleyball, key pressing, and laparoscopic surgery tasks, not pool. In table terms, the idea is to avoid hitting the same cut shot fifty times in a row. Mix cut shots, banks, and position plays, and see whether the skill holds up when the shot changes. That is an application of the finding, not a result anyone has tested at a pool table.

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