Stick Up Cam and Motion Sensor Placement

I am just setting up my Ring alarm system which will replace an ADT system. I have placed a Stick Up camera in the same interior room as a motion sensor. I just realized that there appears to be no need for the independent motion sensor as the camera can provide the same functionality. Is this sound thinking or does anyone see the need for both devices to monitor the same interior room? My ADT system has both devices bit teh camera is under the ADT Pulse functionality. Appreciate your support and thank you in advance