From Wilfred Hughes’ Emacs Command of the Day Twitter feed, we have this useful tip:

Do you have two buffers visible where you want to scroll both of them at once? scroll-all-mode allows you to move the same amount in every visible buffer! — Ⓔ Command of the Day (@ecotd) August 22, 2019

I had no idea this existed. It’s probably not something you’re going to use very often but it’s easy to imagine some use cases for it.