Ever since I've REDUCED my arsenal and primarly focuses mostly on all of the Dynamics of the game first, and understand how to use all of what I have to compliment my game, it's easy sailing.
Doesn't matter if I bring 1, 2, or 8, all about versatility and adjustments first, but again to each their iwn.
I tend to use one ball during a league session, sometimes I will change later in the set to a second ball after the transition, but usually not though. During
shadow is where I decide which ball is best suited for the conditions that day.
I take four "strike" balls plus a spare(plastic). Why? Because I have a four ball bag and it's no more of a pain in ass to take 2,3 or 4 since the bag holds four anyway. Then I have a single ball bag I use exclusively for my spare ball and it always goes with me. So since I have the ability to carry 5 balls, I take five balls. I almost never use more than two and the spare, but it's not the same two every league session. The ball I use as a first(or strike) ball is determined during shadow and at least where I bowl, you don't know what the condition that day will require.
Of course, I can "refer to #3" and bring only my plastic spare ball(or just use a house ball, since the ability to adjust is the only thing that matters anyway) and move my feet, but then my shoes are in the four ball roller at home because they won't fit in the single ball bag and I don't have a locker at the alley and there is no way in hell I'm going to wear the house shoes.
And before someone gets all preachy on me and starts yammering on about using urethane for 10 pins or flattening out on release, etc, etc. Save your breath(or keyboard), because I don't give a rats ass, you do you, I'll use my plastic spare ball, which I use for more than just the 10 pin.
So screw it, I'll take my five balls and not give a damn about what someone else thinks.
Rant to be continued if necessary.