Shrinkage is the workforce-management term for time that is on the schedule but not actually available. Breaks, lunches, training sessions, meetings, sick days, bathroom trips, system outages. In a typical call center it runs 25 to 35 percent of the gross headcount hours.
Every staffing model has to budget for shrinkage explicitly. A team of ten agents on the schedule is really seven to seven-and-a-half effective. Misreading shrinkage is the most common reason call centers under-staff peak periods.
An AI agent has effectively zero shrinkage. It does not take breaks, attend meetings, or call in sick. The implication is that comparing AI capacity to human capacity headcount-for-headcount understates the AI capacity by 30 to 40 percent. The honest comparison is on effective-hours basis.
Vorel headcount math is published on an effective-hours basis. A claim of "the equivalent of three FTEs" is measured against the customer's actual shrinkage rate, not the gross schedule.