The issue is that you leave your caboose on the main track, while you drop off loaded cars. There is a train headed the other direction that isn't scheduled to stop in the next siding. You don't get a signal out of the siding, then you can end up in a stand off.
The key is not to mess around. You need to get past that part of the job before the through train shows up.
I made the whole journey and this one is the biggest CRR dispatcher issue. Do not walk for decoupling - use external cameras
