Gladwell repeatedly mentions the "10,000-Hour Rule", claiming that the key to achieving world-class expertise in any skill, is, to a large extent, a matter of practising the correct way, for a total of around 10,000 hours
2
10
520
5200
You did not reach the 10.000 hours of deliberate practice that would make you great. You could try to:
3.8 hours/day
19.2 years