The diary works in half-days. Two clients can fill a stylist's entire day, so an overrun does not push the next appointment by twenty minutes, it destroys the second half of the schedule.
Cancellations are catastrophic rather than annoying. An empty six-hour slot cannot be filled the same morning, which is why deposits are standard practice in this trade rather than a sign of distrust.
Materials belong to the job. Packs of hair, gel, thread and beads consumed per client are a real cost, and a salon that treats them as general supplies cannot tell which styles are actually profitable.
Return dates are predictable to the week. A style that lasts eight weeks means a client is due at a known time, and a message a few days before is the cheapest booking a salon will ever make.