Not sure about some of this. If you can’t keep a good enough mental model of your book in your head, your readers might struggle to follow it. I do recognise t

Not sure about some of this. If you can’t keep a good enough mental model of your book in your head, your readers might struggle to follow it. I do recognise the issue of nearing the end of writing a book and being torn on whether to include new stuff. In the end you just have to draw the line somewhere. It’s less of an issue if you have an outlet for new stuff - blog, community, etc.