I read a lot of articles but often struggle with books. In attempt to analyze why i came to a simple realization.
Articles published on the web are playing by the “web rules” and value the readers time (another article is only a tab away already open) skipping the unnecessary and getting straight to the point.
The overall length of the work is no problem if the text is divided in chapters/sections that can be wholly consumed during a short session.
Looks like every medium today figured out that short session base consumption is generally liked by the audience. A series of articles is basically a book. Reaching the chapter to the end frees the reader to be satisfied with the progress and be done for today.
Thus it would be interesting to make an RSS feed from the book. Split the text by chapters (word count optionally) and daily push a new item to the feed. Like a blog via rss.