Hi, I don’t think the issue here is the buffer time, but rather the booking time slots in your Bookings Settings: https://support.wix.com/en/article/changing-time-slot-durations-in-the-wix-bookings-calendar
You can offer start times based on the duration of your service (1 hour) or in X min intervals (in this case, I see it’s every 30 min). Hope this helps!