Practicing spares during any competition makes zero sense.
The way you groove your 10 pin shot is to throw it over and over and over. That's what builds muscle memory, and gives you confidence that you can make the 10 pin under pressure.
Shooting a 10 pin, followed by a strike ball, followed by a 7 pin, followed by a strike ball, followed by a 4 pin, doesn't do the job.
When I bowl in league, my goal is to win, not to work on my game. I wouldn't bowl with anyone who told me he wanted to practice shooting spares during competition.
Maybe he'll decide to shoot the 10 pin on both balls. Wow, a perfect 20!
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seadrive
Cogito ergo bowl