You can’t limit the recordings right now (from Quick Tips):
The person detection algorithm runs only on videos captured after a motion event has been triggered. Person detection is not running on the camera live stream, so without a motion trigger the algorithm will not run, and therefore you will not receive a person notification.
Person Detection is a filter for Motion Detection Event Videos. This means that, at this time, all Events where a person is detected are subject to the 12-second recording length as well as the 5-minute Event cooldown.
Does the person detection affect the event recording cool down time?
No, there will still be a 5-minute cooldown between event videos of the same type. If a person is in the camera’s field of view during the 5-minute cooldown it will not be detected.
I’m guessing the reason is because the on device AI algorithm takes some CPU time to process the recorded clip to look for a person and that the person detection can’t be done in real-time on the device right now.