Chapter 13 is about prepping the outline for your speech. The chapter first talks about a working outline vs. a speaking outline, as the former is a way to gather what points you want to make and organize them and the latter is a way to condense the points into a speech-ready format to actually use while presenting. I had never thought about using multiple outlines, as I am not the most prepared person in the world, but thinking about using multiple would be a really good idea. I think this is a really good way to get all your points under control, and give yourself more working room. Using both sets of outlines can give you a sense of how the speech flows, and what parts feel most important to the speech vs. what can be taken out. This gives you an assurance or preparedness and multiple levels of work to draw from to inform your speech.