If you touch type then learn the OS X shortcuts of CTRL-B, CTRL-F, CTRL-P, CTRL-N, far more efficient than moving your hand over to the arrow keys and works in (virtually) all places you are editing text.
I don't think I have anything special configured for my Mojave setup and these seem to work for me. In particular, I use Ctrl + Shift + F2 (on my external keyboard) to focus the menubar and then I can use Ctrl-b and Ctrl-f to navigate back (left) and forward (right) between menus, Enter to select a menu, and then Ctrl-n or Ctrl-p to navigate next/previous entries in the menu, with Enter again to select.
Interesting! I always use Cmd-Shift-/, which focuses the search field in the help menu, and Ctrl-b and Ctrl-f do not escape from there.
But focusing the menu bar with Ctrl-F2 does indeed allow me to use Ctrl-f and Ctrl-b. And after hitting Return to open a menu, I can use Ctrl-n and Ctrl-p to navigate down and up.
Interesting.
I will have to try more, but I still think that there are places in macOS where Ctrl-b and Ctrl-f do not work, and I have to use the arrow keys, instead.
