Hours is enough to empty them. If I see them parked in front of our house late in the evening, I don’t think they’re going to go out anymore today. It’s far more likely that they forgot to turn them off than that they intentionally kept them on.
Fortunately, they rarely flash, but burn continuously. I think the flashing ones are illegal here, and they can be super annoying.
Ah, it’s just a fancy ad. That explains the poor writing.