I have a 5 game practice session that i usually do 2-3 times a week when not bowling league.
Game 1: first 5 frames 7 pin on both balls, last 5 frames 10 pin on both balls, in both cases trying to pick only the 7 or the 10 clean (aim small, miss small). Main focus is form, accuracy, and getting loose.
Game 2: I play a game of low ball, alternating corners trying to shoot the lowest score possible witout missing. Main focus is accruace, form and balance.
Game 3: I spend game 3 using my plastic ball (i have one for practice and one for competition) with a piece of tape on my pap (visual reference) working on a specific thing that I struggled with in the past few days. For instance, my timing, push off, hand position, release, balance, etc. I pick 1 and focus on that 1 until I am comfortable with it again, if I have any frames left I move to another aspect. I use plastic because its cheap. I only care about the first 25-30 feet of the shot in this case.
Games 4 and 5: I usually will put all of the aspects together in games 4 and 5. I'll shoot the strike line that i will be playing on in my next contest (league or tournament) with my plascit ball, only caring about the first 25-30 feet of the shot, then I'll pick a spare. I cycle through the spares, shooting a 7 pin, a 10 pin, a 4 pin, a 6 pin, a 2-7, a 3-10, and so on, all the time trying to hit my target pin dead on. This gives me a chance to maximize my shots per game, and gives me a chance to work on strike line and form and spare shooting at the same time.
This has worked well for me for the past few months that I have really been working with this routine. From time to time I will double the game count for conditioning or to really work on something, depends on if there is tournament that weekend or not.
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"...do or do not, there is no try."
St. Louis USBC Sport Bowling
Best Bowling Pro Shops Inc., St. Louis MO.