The calendar for me is a coordination tool between me and many other people. Other people can see my calendar, too, and see whether I am available or not.
I guess it also depends on the office structure, I'm very lucky that our team is just the right size for a single secretary who coordinates our calenders if we ask.
I'm working in a project with around 4000 people across 330 teams and quite a few different sites in a comm-heavy role - time blocks on the calendar to get work done can be a necessary survival tactic :-)
