How could I resist tinkering?
I said I didn't have time to work on this any further before the end of the jam, but here I am, up way too late messing about with it.

I've added a slider to allow the player more freedom over the kind of game they play

For one, a faster game means more bounces per round, but fewer "balls on the pitch" at one time, since it's harder to react to them all.
Or, a slower game allows more control over the ball and more balls on screen, but with a lower bounce per second.

This came about basically because the balls moved a lot quicker inside the unity editor than they did after I'd built and uploaded the game. Once it was uploaded I decided I didn't mind the slower pace. It builds up very slowly, but suddenly I was juggling six balls, and I kind of felt that was more fun for me. But I did miss the speed and I felt a balance could be met. Instead of playtesting speed multipliers over and over, I added a slider. Why settle for one or the other?