The key is the most sensitive object in the business. Who holds which, since when, and what happens when somebody leaves the team belongs on record before anybody asks.
The time slot is the product. Twelve to two, three days a week, always the same walker: the software has to hold recurring appointments rather than count one-off bookings.
The record after the walk is the invoice. Time, route and a photograph take follow-up questions to zero and extend the relationship by years.
Groups are a rule, not a list. Which dog walks with which, who has to go alone and who cannot cope with males is knowledge that must not live in one person's head.
Vaccination records and insurance carry expiry dates. A system that reminds in time prevents the day a dog walks in a group without valid paperwork.
Billing here is small amounts in series. Ten-walk cards, monthly rates and cancelled outings only stay clean when they are automated.