I have a number of customers that for what ever reason require their PMs done on a certain schedule, like when they have a "down day" and don't need the trucks that 1 day a month, or when the ship is in port. We don't consider this to be "when we are needing something to fill our day" but a -scheduled- service that MUST get done on the scheduled date (after all, we said we would be there at the proper time and date), We do NOT charge more, but these dates are scheduled for a year in advance. This is not quite the same as "at our convenience and only when we are in the area" but it is a _scheduled_ service, and not a breakdown service. We also charge the same (prevailing) labor rate as breakdown service for anything we repair at the same time.