Their method actually does make sense, you just have to remember they aren't cops to solve (boring) crimes like petty theft. Why get it done as efficiently as possible when you can milk it for hours of overtime? 12 hours of footage means 6+ hours of overtime even watching it at x2 speed, and it's the kind of thing you can basically have going on in the background. Cops being willfully ignorant for their own benefit makes sense to me
You know what's even better than milking it for 6hrs of OT? Saying its "to hard" to the victim, going home and then lying about doing 6hrs of OT and getting paid anyway.
Cops lie about OT systemically. Its absolutely rampant. The only consequence they ever get is either a few hrs suspension without pay or fired, and most states are happy to hire them next door immediately so they can do it again.