Why doubled shimmed pockets? That does not make anyone more accurate and consistent than if there were ten inch pockets. Personally I like to shoot every ball in the center of the pocket, no matter the size of the pocket.
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Exactly. On every shot, I teach my students to say on every pot, middle, right or left side. You train to hit the centers like the pros. If they touch a long rail or a point coming in, I make them consider it a miss and shoot it over and over until they pot perfect. It all about training and discipline and not just banging balls around with out a plan or purpose.
I used to begin my day on the 5x10 snooker table, I would toss out 15 pool balls and play until I potted 60. That would have my aim super tight for the day. When I went over to the pool 9' table the pro cut pockets then looked like bushel backets.