Billrob,

There are a limited number of sailing weekends in a year to be used by hundreds of different fleets.
We have cold weather, Dog Days, Hurricane season, etc.
Many Fleets have to coordinate with a Yacht Club or other organization and their needs.
Trying to coordinate all regatta dates at a national level is impossible and impractical.

I have been involved with Hobie Division 9 for ten years.
There are 13 Hobie fleets , of which nine held regattas this year.
They hold an annual meeting where they make the schedule for the next year.
Even a group this small ends up fighting over dates.