[Ataraxic]

If you need to manage multiple windows in emacs I find ace-window perfect.

Pops up a number in the top left of the window and you hit it to jump to it. If only two, C-o works as before.

https://github.com/abo-abo/ace-window

I have never used more than like 5 windows and only for a short time. I guess it doesn't work past 10 but that's gotta be enough for anyone...