ancientaviator62, the (we) Ozmates used the Nav because he was the only crewmember without a job during the start sequence.
I saw a film clip of a Herc to Herc buddy start on a supposedly clean apron area once (USAF or possibly USMC, I think). Even with the high wing-mounted engines, the amount of crap that was stirred up was quite unbelievable, and I understand the rear airframe suffered considerable damage. They were very much a "the yellow hordes are coming through the wire" procedure in the RAAF Herc squadrons - actively and quite strenuously discouraged.