Do most school teams have this type of set up?
I never talk about having a set number of spots. We just stop taking people when we run out of kids with legit potential. I feel like saying "we're only taking 20" would limit me if I had 30 kids who I thought could eventually be important to our program. If I cut those kids, I'm afraid they won't come back.
In reverse, "we are definitely taking 20," would force me to take 4 or 5 that don't have the ability if I only had 15 show up with the right talent mix. Then I'm giving false hope, and putting a parent in a position where they have to purchase warm-ups, etc that their child may only get to wear for one year.