I don't think a true luxury hotel, charging at luxury levels, gets an off day, any more than a Michelin 3* restaurant gets an off meal. Or, to put it another way, if they do have an off day/meal, the hotel/restaurant better find a way to deal with it immediately, to the guest's satisfaction.

The guests at these places are usually not Saudi Arabian princes. They are ordinary people who don't live every day in super-luxury, there for special occasions, and it's a big deal for them. They expect excellence, are charged for excellence, and better get excellence. Consistency IS an absolute requirement and a very reasonable expectation at this level.