Ad schedules for B2B services are an old manual-bidding habit, and with Smart Bidding as the default I'm not sure they still earn their place. The algorithm already sees hour and day in every auction. A hard schedule that cuts hours it would have bid low on anyway just removes volume it could have used.
Where schedules still matter is when the business can't act on a lead outside hours. A plumber with nobody answering at night pays for leads that go cold, and the conversion data has no way of knowing that.
So my view is don't cut hours to save money. Cut them when after-hours leads are measurably worse, and if the problem is only lower quality, a bid adjustment is the cheaper move than a schedule. Anyone seeing the opposite on lead gen with small volume?