It's the timing of our classes 8-12, then 12-1 is lunch break/go home. The interview day is scheduled in such a way that your down time is either during class or late in the afternoon when we've already gone home. Occasionally we chill in the lounge late playing ping-pong, so I recommend not reading anything into the quietness. We're either partying in the lounge, studying in the library, home sleeping/just not aware of when you're actually available (when you're away on the tour, in presentation, or interviewing).
Really the only thing you should get out of this is that 8-12 is awesome, and we're all active doing something other than sitting in class.