In my (first CX) race yesterday, I noticed a lot of guys would enter and exit the corners with a pretty wide line, and also brake heavily and coast through them.
I was able to almost effortlessly pass a lot of guys by merely using skills I learned from crit racing, i.e. set up for a corner more inside/take a line closer to the apex, and pedal all the way through the corner. It was easy enough that it made me wonder if I was violating some unwritten code about passing on corners. Or maybe it's just a C division thing.