I'm using Emacs since 10+ but the one thing that never worked for me is window switching with more than two windows. Do you use C-x o to switch between multiple windows or what do you use?
That's what I currently use to switch quickly:
(use-package ace-window
:defer t
:init (key-chord-define-global "ii" #'ace-window)
:config
(setf aw-scope 'frame))