During the summer months I go twice a week. I work at the alley so I am able to put out any pattern I want. Rule of thumb for me is summer months no ths. Usually I bowl three or four games and then my buddy and I try and leave different spare combo's for the other to pick up. So about 6 to 9 games a week for me.

Depends on my schedule, if a tournament is coming up I typically run a mini camp, unless I feel I need a break during a long stretch of tournaments. My mini-camp usually consists of 10-20 games a day on a sport pattern working on various things depending on what I know about the tournament and venue I will be bowling in. During this time I attempt to mirror what I will be bowling on and attempt to set up my arsenal for that shot, but always remembering to have equipment ready for the opposite extremes if I'm not familiar with the house and how a pattern typically plays or breaks down there.

As far as the unlimited pass, even if the lanes aren't fresh, it's always good to get in there with a spare ball and just get extremely confident that when it matters you can go straight at your spares. You can even bowl for score with the white dot as there should be enough friction present that you can use your spare ball, but still be punished for poor shot making.

I practice more when I know something is wrong in my game (footwork, arm swing, whatever).  I'll work through my kinks and hopefully be prepped for league/tournaments.

If I'm feeling good about my game, I try to practice on difficult patterns.  I know a few alleys that put down crazy shots for me, but in the instance I can't get that I'll bowl on lanes that are destroyed from open bowling.  Take my plastic and just try to repeat a shot over and over.  

If you're practicing for score, don't bowl any more than 6 games.  And on your last game of the session, play Low Ball.
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Proud Supporter of Rob Stone
Obviously, you aren't a golfer.
Some stayed in the foothills, some washed logs like teeth.