In the heyday of those 80-100 car trains on the NWP, swing helpers were used over Ridge Summit in both directions. During the day, a pair of SD-9s helpers could often be found at Redwood Valley, awaiting the northbound (RR eastward) train of empties, to be cut in as swing helpers for the lift to Willits. As traffic declined in the 80s, the helper jobs were abolished and it became common practice to double the hill.
Trains headed for Roseville or Colton were pre-blocked in Eureka and Willits, and generally stopped in Schellville for the crew change. A car or two might be set out or picked up at the Sonoma Pacific spur (vestigial remnant of the SP Santa Rosa branch), otherwise entire consists including power ran through Schellville yard.
This Wherezit? photo location is all too recognizable for NWP fans here on AP.