Most people aren't available at 3am on a Saturday, yet as it stands right now, everyone would be displayed as such. We need a way for individuals (and the admin, for global default) to set "work hours" that are available by default (if any), and "closed" hours. The latter would not be an event, just a default "I'm not here at all."
Then, the "Away" and "Sporadic" events would actually have some degree of relevance, and it would take a major load off of {T2896}.
Case and point, an individual might say he is "available" Mon-Fri from 10am to 6pm. The rest is blacked out by default - he doesn't need to create an event to black out Saturday/Sunday. Then, he can add his events on top of that.