That's exactly it! Outside of tactical uses, it gives a captain an option for turning a cumbersome vessel through the wind while making minimum leeway toward a potential danger. Just imagine using the ship cards to turn from having the wind square on your port beam to square on your starboard. If you jibe or wear (turn away from the wind), you end up moving several inches further downwind before you have changed course. At least by box-hauling (the second hour-glass), you are moving away from the danger (all-be-it slowly).