The GMs currently host events as time permits them and there will be server-wide events once the new source is fully implemented. Not really much more they can do. It's just being lucky enough to be on when they're hosting atm. Otherwise, I don't know if ATW is still being run, but that was a monthly event that has a specific schedule.
They used to host daily events until it caused major lag problems. All the people CCing and in one map made the event virtually unplayable. As far as I know, the plan is to get the new source out and start hosting GM events again.
