Adwords Maintenance - Why a Saturday Afternoon?

The majority of Google staff work only during the day, Mon-Fri, which is at complete odds to their 24/7 service and the importance of it to so many businesses.

If a hosting company wants to upgrade their service, they tend to do it at 2am or 4am or thereabouts, a time at which it will affect their customers the least.

So why does Google do their AdWords Maintenance on the second Saturday of each month, 10am to 2pm PST?

My guess is that weekends are quieter than weekdays, so their staff make a BIG sacrifice to do this on a Saturday morning. But there's no way they could possibly do it at 2am, when it would only affect a fraction of the daytime users. No way, not even if you paid them big bonuses. Probably because they are all multi-millionaires by now and we should be grateful they work at all!