In college I wrote a script to register for classes. I'd input the potentially-full classes I'd like to register for, and it would just hammer the registration site repeatedly until someone removed themselves from the class at which point I'd be registered. I'm still amazed IT didn't pull the network connection to my dorm room or have any kind of rate limiting. No 8am sessions for me!
I occasionally hear about students in US colleges having to compete for places in classes like this. How does it happen? Why does the college admit more people than it has class space for? In the UK they don’t enroll more people than they can teach so everyone has a place.
Additionally, the competition is usually for desireable time slots, rather than to get into a class at all.