Better Way to "Catch" Multiple Slicer Selections in a Formula

A Popular Topic
No, I don't mean things like "Fox Urine" or "Face to Anogenitaled" - those are pretty funny of course, and they come up in my job because I consult for my scientist neighbor on his lab rat projects.
But no, I'm here to talk about something even more popular than Fox Urine Smile
Every day, one of the most-read topics on this blog is some variant of "I want to catch slicer selections in formulas." This has been covered in at least three different posts: