There's also a few tracks were it's not a good thing to put out the circuit maximum number of riders because of the bunching and inexperience in certain groups.
Some TDO's put out the max regardless, at least one that I know of will put out less than the circuit max if they think it would be a safety issue.
That's why it pays to know a bit about the TDO's so you know what you're getting when you book.