I used to use all the balls that I have, only if there is no one playing at the area.
But if there are other people playing at the area, I don't want the balls mixed up with others, or stolen by their kids (it happens). So I'd use just 5 to 10 balls.
The fenced-in area is big enough (3 courts). With only 10 balls, collecting the balls is really burdening us.
If any of you have the same experience, what will you do to avoid collecting the balls so often?