You can have it anywhere you want the cut. I use to have an 03 2388 and I would keep it on the fine cut using a 12 row header. I had no problems with the chopper. The stalks would wrap around the spinners though. It wouldn't do anything but I would cut them off once a day.
We run a 2388, we have an 8 row all crop we use on it. We set the chopper on low speed with the blades all the way open (coarsest cut). And away we go, works just fine just doesnt really do anything. We also remove the spreaders from the back and just drop the stalks straight out the back. Really helps keep that fine dust down. This will be our 3rd year doing it like this.