I've been fascinated for a while now at how layout owners and operators handle large ops sessions requiring many people to work together to simulate a days worth real-world operations. I'll admit it's a part of the hobby that remains largely beyond my understanding. (Though I'd love to take part in a large ops session one day) That said, watching nearly two hours worth of operations unfold on Mike Confalone's Allagash Railway does a lot to shed light on how a well designed operation session unfolds. Here is a link to a free preview of the video.
If this captures your interest, I highly recommend you subscribe to Trainmasters.tv. It's full of fun videos like this and the production is outstanding.