When you spend 7 days, 20 hours per day using Pro, and getting frustrated with it, one comes up with all sorts of great ideas:
I recently had to deal with a lot of maps and a lot of layouts simultaneously, and make many and rapid changes to some or all of them, or direct others to do so, or send them to various production outputs. By my math, I could have been doing 18 hours per day if:
From the Catalog View, I could drag a map to a (new and not-open) layout that I just spooled up in Catalog Pane by copying and pasting it.
Yes, I know I can open a layout and specify a map to use (as long as it's in the project) or drag the map over to it. Yes, I know I can use map series, but not in this particular situation.
The situation I had was, I'm generating a bunch of layouts based on a specific template. Each layout is going to get a different (but similar) map. Perhaps each one just has a different extent, or definition query on some vector data. Opening 20-30 layouts and specifying which map each gets kinda slowed me down.
This is only valid if the layout contains no map. Thing will get squirrelly when you start adding multiple maps and map frames to a single layout using this "drag" method.