It really depends on the school culture and your KPs. When I was a young officer, I will go home if I have nothing on and when I became a KP and RO, I always emphasized to my reportees to go home if there is nothing on for them. Staying late in school just for the sake of it is a concept that I am not able to comprehend. I will only stay if I absolutely have to as I have a life outside of school.

Now as a HQ officer, usually we will still knock off on time but there is always exception as sometimes we have to rush out work and clear things with our bosses.