I guess I was lucky. My workbench, a product of the previous homeowner, was too thick to allow use of the typical plastic clamp that comes with the articulated lamps. While I'm not a great fan of electrical cords snaking across the benchtop, I decided that, for best illumination flexibility, holes in the (already well ventilated) bench top would be best. I liked the result enough that, later, when I resurfaced the benchtop, I redrilled the holes. I never bothered to put in any bushings because the lamps aren't moved frequently and I consider the benchtop a sacrificial surface.
If you ever need to mount a lamp on the edge of a table, I suggest you replace the crappy plastic clamp with one of the design shown in the picture. It consists of a piece of steel bent into a U-shape with a hole in the bottom threaded to take the clamping screw. The top has a large hole in the top that fits over a tall bushing with a foot on the bottom. The original bushing that came with this commercial clamp was made of plastic and soon broke so I turned one from aluminum. This clamp has worked flawlessly for at least two decades.