Personally, I have found that a ball change is only a very short term correction. Face it, toast is toast. If you're playing an area that the other 5-9 bowlers have all been pretty much playing on all night and moving away from, they are doing this for a reason.. Changing balls MAY give you 1-2 more shots in that area, but in my experience, unless you're going from a particle ball to plastic, that's about the most that you will get out of that ball change.
There ARE times where a ball change is needed along with a line change simply to get the right reaction on a new line, for instance, if you were using a piece of equipment that rolled early, but all of the sudden, you find yourself playing a fade shot, you're not going to want to keep that ball out that's rolling early. That's the quickest way to leave an 8-10 or a lilly that I know of.
Bottom line, as far as I am concerned, stick with what is working until you get to a point where you know the ball will be unable to perform for the area/line that you are playing.
