This trigger can only fire once per appointment. So, if your Zap fires, and then your appointment gets rescheduled, it won't fire again for the new appointment time. To check if an appointment has been rescheduled, click on that appointment in your Acuity calendar, and "view changes & notifications sent" from within the appointment details.
If a recurring appointment is made in Acuity, the New Appointment trigger will trigger once for each appointment scheduled at the time of the scheduling.
The Acuity API does not allow for more than 25 subscription webhooks to be enabled for any single Acuity account. As a workaround, each Acuity user can add multiple users to any Acuity account to work around this limitation.
If you run into this error, please feel free to contact support, as we can add you to a feature request to increase this limit.