It's sort of relevant to my original topic, but it's another iHeart90's Weekend on 98.1 WKDD this weekend! As is the status quo with any major holiday where the offices are closed, they've shifted into iHeart90's mode for Labor Day. I'd expect the next one to happen with Thanksgiving, although that might be when/if they switch to all Christmas music.
New Year's Day is definitely another one, and I think Easter is the next one after that, followed by Memorial Day and July 4th, so that's, what, six times a year they do it?