Should You Record During Certain Hours Only?

Have you ever worked on any systems that only operated during certain hours? For example this city will only run cameras from 10-6 for privacy reasons. A school district in Vermont used to only run the cameras during hours no one was at the school (but recently switched to 24 hours). D.C. used to only use them for special events. I think it's clear that more/most people with cameras are running them 24/7 because you don't know when something worth recording going to happen, but I'm interested in learning about cases where people chose to only operate them during certain hours and why.

What we usually do is record during the normal active hours and outside of that record on motion only with a 3 second pre motion and 5-10 second post motion. This eliminates missing anything during the off hours but minimizes the impact to video storage.

Was the primary reason for this to reduce storage requirements?

Since there is really no benefit to having video when nothing is happening, it didn't make sense to continuously record. Changing to this set up allowed for less storage but it also gave us the option to increase frame rate, resolution, etc. since we had more storage freed up that we could utlized. It is a matter of priority specific to each scenerio. One thing we don't do is set a status quo for all cameras. Each camera is addressed specific to that cameras intended objective.

What undisclosed is describing is fairly commonplace (and sensible). What the examples in the OP are doing is not recording at all, which is a lot different, and a little crazy to me.