How often do you refresh a polished ball ?
I'd suggest around every 9 -12 games, keeping in mind that polish i snot a coating but a finish on the ball. That finish gets changed every time you throw the ball. The degree of change depends on your rev rate, how worn the lane surfaces are on which you bowl, and on how much oil/dry you bowl.
You should keep an eye on your track AND on the ball reaction. If the ball reaction is not due to a change in the lane condition, then go by it first, then the appearance of the surface. Learn how soon your polished surface changes, being aware how much of a gloss or how little a shine you have on your ball.