The motion alerts are nice for quickly finding the action. But as
@bigredfish said, having full-time recording assures that you capture everything that you need, even if it hasn't yet triggered an alert or if the movement stops for a while.
And you can have both (at least you can with
Blue Iris... I can't speak for how the NVR systems work). So you have the best of both if you record full time, but also set up motion alerts.
This makes setting the motion detection a lot less critical.
HDD space gets cheaper and cheaper.
I've had events where I had a camera set to only record on motion, and ended up wishing I had full-time video for periods of time when the subject remained largely motionless or was small enough to not keep the recording triggered.
But there are some cameras in my system that I do set up to only record on motion. I need to add more HDD space, myself!
