Every scheduling template for a service business is a grid of slots. Some of them colour-code the technician and a few total the hours at the bottom. All of them fill the grid from the duration the job was estimated at, because that is the only duration a booking system holds at the moment of booking. That single assumption is what makes a full calendar and a deliverable week two different things.
Northgate Mechanical is an invented four-technician plumbing and heating business with 160 paid hours a week and 1,050 jobs in twelve months of records. Its calendar computes room for 47.36 jobs. The week delivers 37.95. It is booking 44, which sits between the two, and that is exactly why nobody can see the problem: the calendar reads 93.6 percent full while the week consumes 114.4 percent of the hours that exist. Both readings are correct, and both come out of the same register.
The 23.10 hour difference is not a busy week. It is 438.90 of overtime premium and 6.05 jobs of backlog, every week, which reaches ten working days by the end of a quarter against an advertised lead time of three. It is also concentrated rather than general. Two job types out of six, eleven of the forty-four jobs, carry 62.6 percent of the overrun, so re-estimating just those two closes two thirds of the gap by editing two rows in a table.