Well, life drawing is a great way to get work on storing things in your brain you can draw on (!) when you want to construct things from your imagination esp. i

Well, life drawing is a great way to get work on storing things in your brain you can draw on (!) when you want to construct things from your imagination esp. if anatomical likeness is your goal. However: What I was talking about in my comment was not to recommend any one path to get to drawing from from imagination, it was a lament that the book just does not talk at all about what I am personally getting the most excitement from in drawing: the thrill of the skill of getting things from your head to the page. And you definitely don't need to do classical life drawing to get there. If you look at the Lynda Barry/Ivan Brunetti style of having fun and drawing things from your head where anatomical likeness is not the ultimate goal you clearly can do that without doing a whole lot of life drawing.