To be fair, many houses have reused costumes, sets, props. They're just re-purposed if it's different from the original use.
Oh no doubt, If I was designing a new WD maze I'd have to reuse the prison and the hundred zombie costumes from years past. Not blaming them for that whatsoever. So much of horror nights has been reused that it's fun to go through every year and look for them (billy doll, crouch hallway, spiny tunnel). They're all in good fun
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An easy fix would be the addition of Horror tracks to Rockit during HHN. It would make the attraction more desirable to "must-do" during the event.
There needs to be some sort of overlay. Even playing treehouse of horror clips in the queue for the Simpsons would make for another reason to go back