Coverage shape
Twenty-four-hour or forty-eight-hour watches with days off between them, an entirely different rhythm from a three-shift rotation, but still a fixed, published pattern.
Qualifications
A base firefighter qualification plus stacked specialist certifications, hazardous materials, technical rescue, paramedic. Each carries its own currency and its own periodic recertification.
Statutory rest
Duty-length and rest rules for shift-based emergency services vary by country and by collective agreement. No specific limit is stated here.
Demand pattern
Minimum crew per apparatus sits close to a hard floor. A department rarely tolerates running an engine below its minimum crew the way an office tolerates being one desk short.