Gotta remember that the road El Coke is talking about was largely line haul from Alamosa to Durango with very little switching in between. The trains were usually blocked in Alamosa for the entire trip to Durango and vice versa. They might pull and set a few lumber loads at Chama or set out an empty drop bottom or two if they dumped cinder ballast enroute or maybe make pickups and setouts at Monero for coal, but there were very few opportunities to work industries from Antonito to Durango. With few exceptions what rolled out of Alamosa rolled into Durango. Same for the return trip. It was easy to block loads at the front and empties in the rear.
Actually, it was usually all loads westward and all empties eastward in the last few years. Trains out of Durango might bring a few cars of lumber but little else.