From The Case Against Education:

How People Get Good At Their Jobs

If schools teach few job skills, transfer of learning is mostly wishful thinking, and the effect of education on intelligence is largely hollow, how on earth do human beings get good at their jobs?  The same way you get to Carnegie Hall: practice.  People learn by doing specific tasks over and over.  To get better at piloting, you fly planes; to get better at obstetrics, you deliver babies; to get better at carpentry, you build houses. 

For the unskilled, progress is easy.  Given common-sense conditions, it’s almost guaranteed.  In the words of K. Anders Ericsson, the world’s leading expert on expertise, novices improve as long as they are, “1) given a task with a well-defined goal, 2) motivated to improve, 3) provided with feedback, and 4) provided with ample opportunities for repetition and gradual refinements of their performance.”[1] Before long, though, the benefit of mere practice plateaus.  To really get good at their jobs, people must advance to deliberate practice.  To keep learning, they must exit their comfort zone – raise the bar, struggle to surmount it, repeat.  As Ericsson and co-authors explain:

You need a particular kind of practice – deliberate practice – to develop expertise.  When most people practice, they focus on the things they already know how to do.  Deliberate practice is different.  It entails considerable, specific, and
sustained efforts to do something you can’t do well – or even at all.[2]

Attaining world-class expertise in chess, music, math, tennis, swimming, and long-distance running requires roughly ten years of deliberate practice.[3] Even champions only deliberately practice for two or three hours a day, so ten years roughly equals ten thousand hours.[4]  Malcolm Gladwell famously dubbed this the “Ten Thousand Hour Rule.”[5] Reaching the pinnacle of achievement in writing and science takes even longer.

Fortunately, the labor market offers plenty of sub-pinnacle opportunities. A few thousand hours of deliberate practice won’t make you a superstar, but is ample time to get good in most occupations.[6] What really counts, of course, is not the mere passage of time, but the amount of practice.[7]   

The Ten Thousand Hour Rule is widely seen as an intellectual victory for effort over talent.  This is a serious misinterpretation.  The Ten Thousand Hour Rule doesn’t say that anyone can become a master if he tries hard and long enough.[8]  What the Rule says, rather, is that even the best and brightest must spend years practicing their craft to reach the top.  People don’t become skilled workers by dabbling in a dozen different school subjects.  They become skilled workers by devoting years to their chosen vocation – by doing their job and striving to do it better.

[1] Ericsson, 2008.
“Deliberate Practice and Acquisition of Expert Performance,” Academic Emergency Medicine, p.991.

[2] Ericsson, Prietula, and Cokely, 2007.  “The Making of an Expert,” Harvard Business Review, p.3

[3] Ericsson et al. 1993, p.366. 

[4] Ericsson et al. 1993, p.391-2.

[5] Gladwell, 2008. Outliers.

[6] McDaniel, Schmidt, and Hunter. 1988.  “Job Experience Correlates of Job Performance,” Journal of Applied Psychology finds that the effect of job experience on job performance is especially strong for workers with under three years of experience.  For more experienced samples, the effect substantially shrinks, suggesting that most workers approach their peak performance after a few years of practice.

[7] Quiñones, Ford, and Teachout.  1995.  “The Relationship Between Work Experience and Job Performance: A Conceptual and Meta-Analytic Review.”  Personnel Psychology find that all measures of work experience predict job performance, but direct measures of the amount of practice are markedly more predictive than time on the job.

[8] See Ericsson, 2012. “Training History, Deliberate Practise and Elite Sports Performance.”