This page curates the research on the above subject
K. Anders Ericsson, Professor, Florida State University, Deliberate Practice
The seminal paper which led to Malcolm Gladwell popularizing the 10,000 hour rule.
The main thrust of the research paper is that the difference between expert performers and normal adults is a life-long period of deliberate effort to improve performance in a specific domain.
The critical element of deliberate practice was that the focus was on a specific skill which one is trying to master.
The implication hence is that an overall area is broken down into a specific skill which you are attempting to master.
What is not generally known is that Ericsson also stressed on setting measurable goals, feedback to performance and a coach who can provide the improvement areas.
To qualify for deliberate practice, all these elements had to be in place along with the dedicated time every day to a guided practice.