[dragonwriter]

> If a factor was properly isolated you shouldn't have to do that one again.

This assumes that later code changes don't undo/blur the factoring, which while ideal is not at all consistently the case in the real world.

Refactoring is a little over arrow of a name, because code hygiene is more than just isolating factors, but the “re” part is right because you are always aiming to remove infelicities that were actively added in previous coding.