Quoted from JethroP:

I'd much rather use a readable paper schematic than a PDF online. Too much moving the scan around on the computer screen looking how things interact, whereas on a paper schematic you can just follow the lines. As stated above, paper laid out on a large surface, under good light is the best for me.
Sometimes the paper schematics don't work well....for instance, if they are actual blueprints, they tend to fade with age, or if they are blurry. In that case I opt for a clear scan PDF and spend the extra time and effort using the laptop.