The more I think about it, the more I don't know if there's really even a reason to fully rerun the events, I guess?
Just give access to the story and the facility materials boss for the old stuff, because that's all that actually matters. Then just add the new event for this year. There's no real reason to rerun the old challenge battle points ladder for everyone, and if you just let the old materials boss stick around for a longer time it should be pretty simple for players who missed it to casually get the old facility.
Maybe this is just some amount of slowly built up frustration with reruns/the two event types suddenly leaking out, but I think it'll feel a bit too much like outright padding to have the entire Halloween challenge battle again instead of something new, only then to then do a new Halloween event again in the next month. Better to just let new players access the stuff they missed without having the expectation that new players will be going through it too, is my feeling.
Of course, we've talked about this before, but some kind of permanent event log + access to the materials bosses feels like it'd be a good idea for facility events at this point. Could even offer the challenge battle with the points ladder, it just only refreshes the one time when it's added instead of being a thing that's theoretically rerun repearedly. Hmm.
