I'm a Guider. As a Guide I was told, and now I'm a Guider, when we do activities about the emergency services, we always tell the Guides to give landmarks with the address. The explanation given is in case the help coming is from a different area because something major could be happening so coverage is shuffled along. We also got taught/teach that if we have enough people and it's a hard to find place, to post people to point the way in useful places (like the corner of a main and minor road or at corners in curvy twisty estates). It even got ingrained into me to know where the nearest hydrants were. Is that kind of help actually useful and do the landmarks get passed on to you?