Great article, solid advice, and nothing wrong with taking one book as your go-to reference, thank you! I consume less and less advice too, but I still hope to — when the timing is right — learn more from some of the greatest.
However, I’ve realized the most important way to improve my own writing is to analyze my own writing. Go back to what you’ve written, edit fiercely (ugh, adverb, but it has such a nice ring to it!), criticize yourself.
Doubting your own writing, but not too much, is the equivalent of keeping your desk in the corner, I think.
Oh and I recently started writing about writing — besides hoping to put out seeds that fall on fertile soil, I find it helps me ask different questions about my own work.