(defun mw-other-window-repeat (count &optional all-frames)
  "Wrapper around `other-window' to continue to jump to other with key o."
  (interactive "p")
  (other-window count all-frames)
  (message "Use o to jump to next window.")
  (set-transient-map
   (let ((map (make-sparse-keymap)))
     (define-key map (kbd "o")
       (lambda () (interactive) (mw-other-window-repeat 1)))
     map)))

(global-set-key (kbd "C-x o") #'mw-other-window-repeat)