For the customer who comes every fortnight or the colour that happens every four weeks, book the pattern once instead of visit by visit.
Booking a series
In New booking, turn on Repeats. Pick the pattern - every so-many days, weeks or months - and how it ends: after a number of visits, or on a date. Weekly patterns can land on more than one day: tap the extra days and a treatment plan like Monday and Friday for six weeks books as one series, every visit at the same time. Series can run up to a year ahead.
Before anything books, every date in the series is checked against your real calendar: closed dates, time away, rosters, and existing bookings. Dates that fit tick through; for any that don't, you'll see that day's genuinely free times to pick from, or you can skip that one. Nothing ever books over something else.
What the customer gets
One confirmation email for the series, saying how it repeats and when the last visit is - then a normal reminder before each visit. Every visit is an ordinary booking: it can be moved, cancelled or edited on its own, and it keeps the policy it was booked under.
Ending a series early
Open any visit in the series and choose End the series: every remaining visit cancels in one go, nothing is charged, any deposits go back, and the customer hears once. Past visits stay as they are. To cancel just one visit, cancel it like any other booking.
Repeat bookings are part of the paid plans.