I pracrice exclusively at home and go out the tourneys or to gamble. In the last year or so, I have completely dissmantled my game and rebuilt it. I had, for a better explaination.....a very McCready like game from starting to play at around 5 or 6. I felt I got to a plateau and needed better fundamentals to excel to the level I wanted, so I "chopped, cut and rebuilt" my stroke.
I am now much more in plane, my grip and hand position is MUCHMUCH better, and my shot sighting is now equal, or neutral.
To get to this point I played almost every day for about 2 hours for the last 6 months. I incorporated aspects I thought would work, and cut out what I thought was hurting me....this was VERY frustrating because I was already a good player....not great, just good.....with some 100+ runs, but inconsistent.
Today, I am on top of the world happy! my game is exactly where I need it, and when I miss, I know why......I used to miss and scratch my head with no clue what happened
So, how many hours? I dunno, but I feel once you get there it's just a feel thing to stay in stroke, but to build a reliable game.....I'd say like me.....a year or so, and 2 or 3 hours a day will do it.....get a good teacher to cut that number down IMO.
good luck,
G.