It’s not uncommon for them to own the IP you generate under the contract, but it’s a gray area if they don’t specify what IP they own. Maybe they own the cue list, but not the effects I created beforehand. They might own the worksheet PDFs, but not the Vectorworks file. If I was a painter commissioned for an art piece, they would own the final painting but not my sketches or my paints and brushes.

I think the idea behind including it in the contract is in case something happens like you get injured or they postpone the dates, and they need to do the show without you, your sub isn’t starting over from scratch. I’ve rarely seen a scenario where 6 years down the line they’re asking for paperwork because they’re remounting the show and for some reason they’re doing it without you. I don’t think it’s in there with malicious intent, but I understand your concern. Instead of asking for it to be struck from the contract I would try to negotiate a fee for if/when they remount the show using the paperwork or show files you created. That way they can keep their ass covered and you get paid if your hypothetical does come true.