Seeing more stopped trains on Wednesdays doesn't necessarily indicate inefficient. Railroads have a weekly cycle of traffic volume, especially at the east and west ends of the national system. They cannot, and should not, afford to have sufficient capacity to handle all trains promptly on the peak day. Doing so would mean idle capacity on the other six days a week. That's the quick route to bankruptcy. What is most important is to have the capacity to handle a week of traffic each week.
Avoiding yard congestion is vital to moving the traffic. It's much better to have trains idle on the main line than to fill the yard so it can't be switched efficiently.
