Capacity and recovery
Educating is physically active and emotionally attentive work, and capacity is not a fixed quantity. It rises and falls with sleep, health, caring responsibilities outside work, the intensity of a particular room or group, and how much genuine recovery has been possible between shifts. When breaks are protected, hours are predictable and there is room to slow down after a demanding period, recovery is better supported. When recovery keeps being deferred, covering absences, finishing documentation at home, moving from one demanding week straight into the next, tiredness stops being something a weekend can resolve.

