Storage demands cannot be defined without a strictly predefined recording plan.
Factors that have to be considered here are recording mode, resolution, framerate, a number of cameras, cameras with AI processing, traffic in front of the cameras, footage demands, etc.
The continuous recording mode is the most demanding feature concerning the storage usage because it saves everything camera records. Storage demands variate and is changeable depending on a case.
Continous recording is always viewed with a HD resolution that is configured on a camera and cannot be adjusted to a lower framerate.