For The Pragmatic Programmers, I shared the story of how making a diagram helped me find a bug in an example. I was working on a chapter of Program Management for Open Source Projects about process design. I included an example process. When I started making a sample diagram for it, I realized I didn’t write it well.
One of the interesting things about writing a book is learning the lessons you’re trying to share with your readers. I almost never sketch out processes when I’m working on them. But it turns out there’s a reason that I suggested it (and it’s not just to make the book a little longer).