Originally Posted by Rhino Driver

The only time you are obligated to check your schedule while on RES is prior to release from the last leg of a rotation, and prior to 0200 on your first on-call day. The rest of the time you are required to be available for contact on LC, and promptly available for contact on SC.
If you never receive a call from ATL, you are not obligated to check your schedule while on call.

Your check every 9 hours assures you will not miss the 3 hour prior acknowledgement window (1 hr for start of SC), but if your phone never rings, there won't be anything on your schedule.