I would expect to arrive and find the FCFS balls taken and the Boaty Balls empty! That's why they paid for BB, so they could sail, snorkel, hang out on a beach, whatever and arrive late to find a ball. You wouldn't pay for a BB if you planned to arrive early.

The elephant in the room is the size of the boats in today's fleets. Some mooring fields were laid out when a 40' mono was a BIG boat. Now there cats above 60'. I am most familiar with MC, and I can tell you things can get very interesting when the winds and currents have the monos and cats laying in different directions.