Maintenance contracts are the quietest revenue there is, and they lapse without a word. Term, due date and contact held on the contract turn an old customer list into February's work.
Refrigerant handling has to be recorded, and the same record doubles as the unit's history. Held per installation, an inspection is a query rather than a day in the filing cabinet.
During the peak the limiting factor is stock, not hours. Order date, delivery and the job it belongs to together show which customer can actually be scheduled this week.