Maybe it's a good business decision. Shut a station down for a few hours once a week. Conserve on electricity,etc?
Er, once a week? I don't think anyone implied that engineers would ever do maintenance on a station that required them to shut the transmitter down every week, regardless of the cost. Owners would sooner burn a transmitter up before that took place. (In fact, I know one who did! lol)
However, if one scheduled their maintenance for the least impact on ad revenue, I'd have to say early Sunday morning through the day would probably be the most opportune.