Here are some hopefully edifying close-ups of a Sickles drawing:
Sickles was assigned to illustrate technicians at work on a nuclear reactor... not exactly an artist's dream assignment. But the resulting drawing shows how Sickles rotated and cropped the image to turn a complex subject into an interesting design.
Sickles' philosophy was, "For reportorial drawing one needs a draftsman, an artist who goes beyond a literal rendering and who interprets and selects. He can often make the slightest sketch significant and can bring life, meaning and vitality to a drawing as well as the imprint of a personal style."
Sickles was famous for his location drawings, which pioneered the trend in American illustration away from "finished" drawings, and toward the acceptance of more spontaneous sketches. This trend was later developed further by artists such as Robert Weaver, Franklin McMahon, Alan Cober, Paul Hogarth and Tom Allen, before it became the dominant style in illustration.
In his excellent book On-The-Spot Drawing, Nick Meglin quotes Sickles on this transformation in taste:
My drawings were mostly observations, details, compositions, ideas and just plain visual notes to myself...a wagon wheel looks like this...an oak tree looks like that. You'd go to an editor with your drawings and he'd say-- "Yes, fine. This is what we wanted. Now go home and do me a finished one." Today he says-- "Yes, fine. This is what we wanted." Then he reaches over and rips it out of your sketchbook and prints it, charcoal smudges and all."
The craftsmanship and technique may not be the same, but as public awareness increases, the demand for the true picture, the natural picture, has become the important thing.
I don't know whether this drawing of the nuclear reactor was done with the aid of photo reference; I do know that if you follow Sickle's pencil line close up, you can see that he did not slavishly follow the line of any photograph when it came to the human figures here.
Even when he draws the machinery, we can see from the detail below that Sickles made a few sparse guidelines with some mechanical tool to make sure the basic structure was squared off, then drew the reactor freehand with a natural spirit using uneven, overlapping and transparent forms.
Sickles knew exactly how tight he wanted to make this drawing, and no tighter.