for navigation through the outline? These are first class keys,
and I would have good uses for these keys if most people don't actually use them.
I found their action difficult to follow. Compare C-left. In most environments, if the cursor is within a word, it first moves to the start of the word, and subsequently moves to the preceding word.
C-c C-b breaks this idiom. I found this so jarring that I gave up using these keys.