You can think about it.
Dave Davis one of the all time greats works on this for almost 45 minutes ever practice session!!!
Doesn't even care where ball goes.
Has an observer tell him every throw. "1 inch, two inches, 1 inch, 2 1/2 inches, 1 inch".
Like that.
45 minutes a day, 40 years and you might have a few major titles also!
REgards,
Luckylefty
PS the same drill has worked for me every once in a while!