How much space do we need—really?

Last weekend, I went for my son's swim meet. For those of you who are new to this concept, parents and their kids flock in thousands in a small area where they pitch their tent or put up chairs to rest and wait up patiently for their kid's turn to go and swim when their event is announced.

Each event has about 20 heats with 7 lanes open. And each child registers for at least 4 events. Thus