Television

It's not even really specific to Halloween, it's more just autumn-themed (a bit wintry in EP10), so it is somewhat less likely that everybody is going to watch it all at the same time (if that even matters, also I'd imagine it takes less bandwidth than the same duration of live-action content).

Assuming content is balanced on different servers, you'd think a highly-acclaimed (for young and old) seasonal (rather than holiday) 10-episode animation series would be the absolute pinnacle of content to have on a subscription service. Evergreen content. Well, that is if it actually made sense beyond short-term money.