Sept. daily park crowds, at both Universal & Disney, according to Touring Plans lines, seemed to be slow like they were before September became busier around 2017/2018. Crowds seemed to be limited to special events like HHN, and a few days at Epcot. I have no access to internal numbers, but my guess would be that HHN crowds are primarily being fueled by locals going many multiple times on the tickets that are relatively inexpensive if you go more than 4 or 5 times. And with what happened after a lid was put on purchases, Brian's theory probably holds up. I'd bet they change the ticket structure next year to discourage that hang out segment of the HHN crowd. Sounding a lot like the problem Disneyland was having with their AP's when the park basically became a hang out after 4:00 PM most days, and just got too crowded to even move.