One of my favorite sections to create in the Mythology book was the Cult Distribution tables. I’ve actually made big spreadsheets of each of the regions to get a feel of the numbers involved, and I frequently post little clips from it here.
For world building, I find those sections absolutely invaluable. If I was writing any Jonstown Compendium material detailing an area I’d definitely read them carefully!
They are also no doubt filled with plenty of surprises (and even “are you sure that is right?” comments)!