I have just implemented it on my caches, but I'm not too clear how it helps. I tend to search for caches near a postcode and get to see the distance in the resultant display. And occasionally I pick on caches from the interactive map and when I get to a cache page I see a small map listing nearby towns.
I have noticed counties in the names of caches, but I guess that I assumed they were autogenerated.
ANYWAY - if that't the convention I'm happy to comply.