I was very surprised to learn that on the stillwater venues, SANA didn't have the funds to reserve all of the boats. I'm not sure about all of the stillwater venues but on Menteith, the Worlds contingent are only using 12 boats and the other 18 are available to all-comers on the dates of the competition sessions
If you weren't able to commit to control on all three days and your controller application is consequently rejected, there is still an opportunity to observe at relatively close range by booking a boat at the Lake or one of the other stillwater venues.