Our gym does both, but fall is much, much smaller. Basically, there is one meet that is available for girls who need a mobility score. But all girls can compete for pre-season practice. And HC lets girls compete, even if they don't have all their events yet. If you qualify (and you weren't just going for mobility), you go to fall sectionals and then states.
By Spring season (which starts January), girls are not allowed to compete unless they have all 4 events.