Basic Query - If you have a NVR is there any point/benefit in also using a SD Card?

Title says it all really.

If you don't wish to, for some reason, or can't afford to purchase a dedicated NVR, then having an SC Card slot in a security cam is a great option.
However, if you do have a NVR which all your camera's connect to. Is there any benefit/reason to also having a SD Card fitted in your camera's
Or is such a setup totally pointless?

Thanks.