I was stationed on a Destroyer from 2015-2017 and subsequently deployed with them as an IT in the radio shack. CIC looks like something out of a movie (and really the only part of the ship that does) - it's very dark, has lots of glowing monitors covered in charts, surveillance feeds, and a whole lot of people. In the radio shack, we worked 12 on, 12 off, 7 days a week. I cannot remember CIC's watch rotation exactly…
I'm really surprised that all it takes to be declared qualified is the signature of someone else who's qualified. That leaves lots of room for slippage and social pressure, like the dip you mention. It also leaves no one specifically responsible for the crew's level of qualification. A cynic might say that was the point of the system: we know this is going to fail, so make sure no one is directly in the line of fire when the shit cannon goes off.