I don't know of any articles they've written about the process, they do maintain a forum where they post extensions to the book (on things that change often, e.

I don't know of any articles they've written about the process, they do maintain a forum where they post extensions to the book (on things that change often, e.g. neural networks) for free. I agree, though I do think that professors evaluate each textbook to make sure it has the information they'd like to teach within it so the issue becomes more of a professors preference- should they provide a reference textbook or a book that perfectly matches their course. In the case of Malik, (I believe) he writes books to fit how he thinks the material should be learned then teaches the courses to match the books. Attending the class would usually give answers to some of the example problems and go through the concepts.