Rack, the "downside" is some guys practice on the "ABC Shot" at home, and they figure out that if they use ball X, playing line A, with speed C, they will score. then they get to the tournament location, and when the shot they practiced seems different, they are too stubborn to move and end up shooting 1400, and spend the whole time saying "This line worked at home, why doesn't it work here?"
Practicing on the shot before you go can help you, but your plan of attack should not lay solely in what you learned at home. It will give you a good starting point, and force you to get used to hitting a 2 board area as opposed to the THS 9 board area.
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The clock on the wall says 3 O'Clock...last call...for Alcohol!
"I love a martini -- but two at the most. Three I’m under the table; Four, I’m under the host." Dorothy Parker