Revs are a big determinant of the distance between flare rings. The ball's differential and where you have the pin in relation to your PAP determine the amount of flare potential. As has been stated, 3 3/8" from PAP maximizes the flare potential of the ball. Given that, a bowler with lots of revs will have more flare rings, and closer together. A bowler with the same ball speed, but fewer revs will have fewer flare rings, and further apart--usually.
Here's another little discussed factoid about flare. It's well known that moving the pin further from or closer to your PAP than 3 3/8 reduces flare potential. Putting the pin about halfway between leverage (3 3/8) and your track, or about halfway between leverage and your PAP reduces flare potential about equally. The rarely mentioned difference is that GENERALLY what flare you get from a longer pin to PAP distance will come later in the ball's path; and what flare you get from a shorter pin to PAP distance will come earlier in the ball's path. (This is a general rule, and is applicable primarily to symmetric cored balls. Highly asymmetric balls like Mo's are subject to their own rules, and I leave that to the experts.) So, you can get greater length out of a ball with a long pin to PAP distance not only because that drilling slows up how quickly the ball will rev up, but also because it is saving most of whatever flare it has for the back. The lesser flare in the heads and mids also contributes to length.
Shiv
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Listening to the monotonous staccato of rain on my desk top
