I use pencils mostly for doing puzzles. I have a set of different ones, because I find there is a big difference between pencils in how well they write on different types of paper. A pencil that does great for the daily Times often doesn’t work for the Sunday Times. I used to be a big fan of #1 pencils for puzzles since they’d write on anything.
I loved Petroski’s book, btw. Did you know that Henry David Thoreau had time to go to Walden because his father was a big pencil magnate? Thoreau also improved the efficiency of pencil manufacturing greatly - he was more of a practical guy than I had ever imagined.