Absolutely agree with this- "The feedback matters and the concentration does, too — not just the hours."

Creative people are different from others, It means they use Out of the Box thinking That's the trait that makes them head and shoulders above the rest. They reach the peaks of excellence..

Basically one needs to be focused and have single minded determination to achieve one's goal and to excel more so...Ultimately what really matters is the satisfaction one derives out of it 

We don't need lot of hours to reach the genius level.  Time is not a matter. Hard work is only the main aspect to get the achievement.

I once heard an eminent speaker from Staff College Hyderabad, say that excellence means doing the same job better the next time and so on till perfection is achieved. He quoted and translated a shloka of Geeta to this effect. In this way he said excellence can be achieved by common persons also.