No rattling here, Acorn.

I do scale some designs. I also export the scaled down PDF itself--no need to increase the design-size. However, doing a scaled design requires communication upfront with the print service so everyone is using the same playbook.

It's just in general if the design is below a certain threshold, I prefer to design at 100%. But if one wanted to scale this particular job, I would use 50% (keeps it easy) and rerun the spreadsheet. Though the attached screen shot is easy enough at 50% scale--just double all the numbers.

One needs to remember that DPI means, well, nothing per se. It's all about the effective resolution based upon pixel dimensions for any given image in the design at its placed dimensions.