I remember Grady Mathews once saying that he believed you had to shoot roughly 2 million shots to become world class. According to the book Outliers by Malcolm Gladwell, many studies show it takes about 10,000 hours at pretty much any endeavor to become great. Which aligns pretty well with what Grady said - 200 shots per hour for 10,000 hours = 2 million shots. If you shoot 1000 shots everyday (in earnest) it would take about 7 years.