I think phrases like "but it's more efficient" is a bit dangerous. I'd
rather want something like "but some feel it's more efficient". It all
depends on the user, his keyboard, his habits etc.
I have yet to see a keyboard with arrow keys close to the rest of the
keys. They are always somewhere on the fringes. So, habits aside,
the distance to C-f is shorter than to the right arrow key, and that
is an objective fact. Of course, people might prefer a less efficient
way, e.g., if they type so slowly that the additional time is
negligible.