I love the reading plans for non-Biblical books. They keep me on track with my reading goals. I wish that there were options included to read 1 Chapter (article/day). This would be particularly helpful for devotional-type books that aren't marked by date but still are designed to be read at a one-chapter-per-day clip. The following screen shot is a good example of what I think should be included

In Piper's Godward Life, designed to be read in 120 days, I made a reading plan encompassing all of the pages between chapter 1 and chapter 120 and I set it to be read in 120 days. Because each capter isn't exactly the same length, the reading plan generator set me up to read less than a chapter some days, more than a chapter on others, and never just one chapter.
There have been many times when I just wanted the ability to mark out a plan based on chapter divisions. (one chapter every 2 days, one chapter per day, etc).