This is the way I see things.
Find trigger words from TOC first. Then find trigger words from chapter titles, and section titles. If each section has their own sub section, find trig words from those sub section titles. Do this progressively until there are no more sub section titles from which to pick trig words.
Second, use all the trig words from TOC, chatper titles, section and sub section titles, and try to connect them together to form a logical hypothesis regarding the main idea of what you are reading. Then try to hypothesize how each sub section fits into the section, and how each section fits into the chapter, and how each chapter fits into the entire book.
Third, you can begin to dip read the paragraphs themselves to pick trig words. But be sure to keep in mind where that paragraph is. The paragraph might be located in a section whose main idea u guessed is about xxx. Then you pick trig words with the purpose of finding out how the paragraph is talking about xxx.
To summarize, it is possible to pick more trig words from paragraphs rather than just TOC. But to do that, you have to have some ideas what the chapters and sections are about. To have an idea of what the chapters and sections are about, you use trig words picked from TOC, chap and section titles. Then you try to guesss the main ideas. Having done that, you keep these main ideas in mind, and dip read to pick more trig words from individual paragraphs.
Hope this helps