For a number of years I was logging contract supervisor for a large timber company. I was responsible for the harvest of 150-180 MMBF/year. The contractors ranged in size from those that moved a couple of loads a day to those that consistently moved 20+ loads /day. Regardless of size, if they weren't efficient productive loggers they didn't last long. The wood ranged in size from 5-10 logs/load to 100+ logs/load - with most being about 30 logs/load.
Even the most efficient and most mechanized of these contractors on the best ground and biggest timber did well to maintain 5 loads/man/day long term, when cutting, de-limbing, bucking, skidding/yarding, and loading were included in the calculation. And that doesn't include a man to keep all the mechanized equipment maintained - if the operators had to maintain their own equipment, they couldn't keep up that pace.
PS
The most productive loggers were those operating in Lodgepole pine clearcuts where 90-110 logs/load were the norm - flat ground, uniform timber size, feller bunchers, grapple skidders, and mechanical de-limbers/buckers.