Maybe I am missing something but why would you ever declare a run when sprint is available?
I have looked at this and can't figure out where within 3 hexes you would ever run to that you couldn't also sprint and make it to the same place and facing.
Which begs to ask why does the differentiation exist?
Perhaps just so moving three or less places doesn't require counting up to twelve?
I don't think Sprint exists for moving up to 3 hexes. But if you want to move a lot of hexes then that is what sprinting exists for.