Because of the varying cargoes and operational circumstances, 
there was a great Fluctuation in the difficulty of the
work performed, particularly in the hold of the vessel. This was
another source of considerable satisfaction. Within the limits of
the usual variety, pace, and cycle of longshore work, the
dirtiest, hardest, and most demanding of such work was for the
most part "gobbled up" by those who were not severely
"taxed." The common posture was, "I don't give a damn what
the cargo is." This reflected a general social definition of
longshoring as "man's work."

Mobility. The variety of work options available to the men
was also very greatly extended by quite exceptional opportunities 
for mobility within the industry and the final (if temporary) 
"safety valve" of not working as a longshoreman at all.