One thing the article does not mention is that the darker (and softer) the pencil, the more easily it smudges. Even if it is not charcoal, you’d do best to fixa

One thing the article does not mention is that the darker (and softer) the pencil, the more easily it smudges. Even if it is not charcoal, you’d do best to fixate if you use really soft pencils like the 12B they tested. As a side note: I love a thick 5.6mm lead clutch pencil for quick notes and sketches in my notebook at work. It writes like a pencil and you can erase it, but it has the feel of a sharpie (thick lines, not very accurate). It forces me to be concise in what I write and draw. But after experimenting there I did settle on #2 lead for most uses. My notebook simply becomes one grey smudge much too quickly with softer leads.