I was lucky enough to know several of the SVRy "old Timers", bit I don't recall them talking about how difficult firing with wood might have been. The late brakeman Johnnie Bates did tell about the different firing characteristics between locomotives. He reported that identical locomotives # 19 and 20 were exactly opposite; one steamed best with a light fire and the other wanted to be "stacked clear to the crown sheet".
In the Baker Yard they had fuel crews to load the tenders but on the road it was up to the train and engine crews to reload fuel, which was done from several wood piles along the right-of -way.
I did not know him but a long time fireman, Fred Hutchens, once reported that he had palmed something like 70,000 cords of wood.