Every animator's nightmare is the crowd scene. Every cartoon "writer"'s favorite word is "crowd". It takes half a second and no creativity to type the word and at least an hour or two to draw one frame of one crowd - let alone having the horror of animating 12 0r 24 frames of crowds for every second of film.
If you HAVE to draw a crowd, here are some tips on how to make one read clearly and look interesting.
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Milt Gross is an amazing designer. Most comic artists, even great ones like Jack Kirby draw just one basic face and body type over and over again-especially in crowd scenes. Who can blame them? In this Gross crowd, every lady, while all following a unified line of action, is a completely different design. Invention just flowed out of this guy's pen.
http://johnkstuff.blogspot.com/2007/10/milt-gross-crowds.html