Some things change frequently [conversations, blog links, project ties] while other things do not [business relationships, friendships, expertise]. So a 'static' map of working relationships in an organization is very useful, and yes we take follow-up snapshots. Just think of an x-ray or CAT scan -- same process, same use [what is going on inside where we cannot see?] Doctor looks, learns, does something, later looks again to see if progress is made.

Karen Stephenson did some interesting research many years ago where she showed that the social networks inside a a large firm were very stable -- more stabel than the hierarchy itrself! The organization went through several re-orgs [the formal/prescribed network changed] but the strong social/trust ties did not change that much -- they held steady from year to year. I still seek Jack out for advice on X no matter where he now works.