When you don't understand all your equipment you have too much.
If you show up with 8 balls, and you know exactly what each of the 8 balls does, and exactly what each little difference in the ball makes, then its fine. If you can do that with 20 balls its fine.
When a woman who has a 100 average, has a Maxim for strikes, and Vis-A-Ball for spares, thats too many as IIRC not only do neither of them have a real core like the XXXL, but she would not be good enough to understand the difference anyway.