Throughout the game you come across "shortcut" doors marked with intersecting squares. Is there any way to predict where these doors will take you without just going through? It seems they are intended as a shortcut, yet they don't seem to show a preview of the destination like normal doors, and the connections don't seem to appear on the main map. This makes them hard to use as a shortcut unless you have a photographic memory of their locations. Am I missing something? Do they serve some other non-obvious use?