It would seem to us that nights and weekends are the most convenient time for citizens to access government services such as this. But the things that are down

It would seem to us that nights and weekends are the most convenient time for citizens to access government services such as this. But the things that are down for maintenance are not our publicly-accessible frontends, they're the backend databases that the administration uses internally as well. So it would seem that all the worker bees in government offices rely on having access to those backend databases during USA office hours, and the only time they can realistically be shut down is while the civil servants are off the clock.