Currently, when you book an appointment with no end date in Scheduler, the system will default to allow the appointment to be booked for six months. However, this date will be extended if you allow clients to book more than six months out. You can modify how long clients are able to book you out on the Business Set up page. This is be done by going clicking on your business name in the top right hand corner of your account-->Business Set Up --> Settings.
Currently, no notification is given by Scheduler if one of these far-out (over 6th month) recurring appointments creates a conflict (if it falls on a holiday, or blocked out time).