Tracks just schedule racing events. They could schedule them years in advance if they wanted to, but they limit the forward scheduling just in case some megabuck event decides to ask for a slot that they did not have previously.
Now consider an autoX venue. If anything else comes along it will normally pay more money than renting to a little car club. Consider a 10,000 person concert that has 5,000 cars paying a fee for the lot. Sporting events and sports arenas. Lots of juggling and hoping, just on the regional level. I can only be thankful I don't have to worry about 3 different series lining up like National has to plan for.