Thanks Charlest, for the comments. I've often wondered if it wasn't the dirt or grime the ball picks up in the pit area or ball return that makes it grab more since the ball surface seems (tacky, sticky) compared to the clean surface. I don't get that as much as places are cleaner overall. I plan to continue to clean my stuff after every outing. My main question was how my friend who refuses to clean his stuff is able to maintain the performance of his equipment over the long haul.
The final answer could any number of possible combinations. Two of the most obvious may be one, that the house pattern often hides huge differences between balls, and, two, we all make adjustments over the periods of time as small as over the hours of a league to years at the same house. Over any those periods of time, small and large adjustments we make often without thinking where we stood and what mark we hit 2 days ago, 4 months ago or 4 years ago.
A good bowler doesn't care what he did in the past; he just learns from it and makes the adjustment in the here and now. Oil amounts change, lanes wear, pins get replaced, polish wears off a ball, managers buy new oil, humidity changes - but the bowler does what he must. Do you know for sure that he stands in the same place and hits the same target with the same ball and the same release and the same ball speed as he did 5 months ago or 3 years? possibly yes, possibly no.
I wouldn't worry about it to much. He does what he does. If you want, leave one ball untouched for a few weeks or months, if you can. Maybe just an old practice ball that you use only in practice. See what happens for yourself.