Customer journey is everything here. Seen too many businesses in LATAM and Europe lose 30-40% of bookings because they treat the appointment as "done" once it's booked.
SMS reminders outperform email by a wide margin in most markets - WhatsApp Business API is non-negotiable for Brazil, Mexico, Colombia. Email gets buried. Calendar invites (.ics attach) help, but only if the reminder actually triggers the native calendar notification, Google and Outlook handle those differently.
Deposits work, but they're a conversion killer in price-sensitive regions. Cancellation fees with 24h windows are standard in Germany and Nordics, but in Southern Europe or LatAm you'll get pushback unless the policy is framed as "we hold this slot for you" rather than "we'll charge you." Framing matters more than the fee itself.
One thing that moved the needle for a clinic chain in Spain: a confirmation flow that required a manual "confirm" tap 48h out. No tap = auto-release the slot. Cut no-shows from 22% to under 8% in two months.