10,000 Hour Rule" make famous in the book Outliers by Malcolm Gladwell.
The article is a review of the book Focus, by Daniel Goleman, who is also the author of several other great books about Emotional Intelligence.
Below is an excerpt. The full article may be read here.
The secret to continued improvement, it turns out, isn’t the amount of time invested but the quality of that time. It sounds simple and obvious enough, and yet so much of both our formal education and the informal ways in which we go about pursuing success in skill-based fields is built around the premise of sheer time investment. Instead, the factor Ericsson and other psychologists have identified as the main predictor of success is deliberate practice — persistent training to which you give your full concentration rather than just your time, often guided by a skilled expert, coach, or mentor. It’s a qualitative difference in how you pay attention, not a quantitative measure of clocking in the hours. Goleman writes:
Hours and hours of practice are necessary for great performance, but not sufficient. How experts in any domain pay attention while practicing makes a crucial difference. For instance, in his much-cited study of violinists — the one that showed the top tier had practiced more than 10,000 hours — Ericsson found the experts did so with full concentration on improving a particular aspect of their performance that a master teacher identified.
Goleman identifies a second necessary element: a feedback loop that allows you to spot errors as they occur and correct them, much like ballet dancers use mirrors during practice. He writes:
Ideally that feedback comes from someone with an expert eye and so every world-class sports champion has a coach. If you practice without such feedback, you don’t get to the top ranks.
The feedback matters and the concentration does, too — not just the hours.
Additionally, the optimal kind of attention requires top-down focus. While daydreaming may have its creative benefits, in the context of deliberate practice it only dilutes the efficiency of the process. Goleman writes:
Daydreaming defeats practice; those of us who browse TV while working out will never reach the top ranks. Paying full attention seems to boost the mind’s processing speed, strengthen synaptic connections, and expand or create neural networks for what we are practicing.
At least at first. But as you master how to execute the new routine, repeated practice transfers control of that skill from the top-down system for intentional focus to bottom-up circuits that eventually make its execution effortless. At that point you don’t need to think about it — you can do the routine well enough on automatic.