I have looked, but cannot find, the source, but I distinctly recall the sales force was told to stop selling to ranchers/sheepherders. The Grande lost money on every stock move starting I think in the late 40s. Labor costs for the stock trains were through the roof. It could take hours to load a train. You had to have a crew on hand for the entire process as only one car could be loaded at a time.
Once loaded, the train had to get over the line as a single unit and to the next major facility to unload the animals due to the laws governing time in the stock cars.
Thus you get the triple and four headed stock movements as a single train.
It was not loading up an equivalent number of gons with coal. You could run the train in sections, etc. and get it to its destination in a more leisurely fashion.