In Writing the Breakout Novel Workbook, Donald Maass has an exercise called Weaving Plot Layers Together.
His exercise tells you to get a single sheet of paper and make three columns. The first one lists all of your characters, the second are all of the things that happen to them, the "narrative threads." This would include their problems, plot layers, subplots, questions that need to be answered, that kind of thing. The third column is a list of your major scene settings.
The exercise, using simple circles and lines randomly drawn on the paper, is designed to help me see more connections between characters and story lines and scenes. I confess the first time I attempted this exercise I lacked any kind of random flare. I didn't let myself go. I was being Data when I should've been Obi-Wan Kenobi.
There is, however, something I want to try. I think all of the circles and lines might make my head hurt, so I want to use 3 x 5 cards. Maybe even shuffle them and see what happens.
Debra Dixon makes a similar comment in her book, GMC: Goal, Motivation, and Conflict when she points out "Each motivation impacts the other. Each goal impacts the other. Whether you paint the relationship between multiple goals with a broad stroke or with subtlety, the result is worth the effort. You'll have a more complex book and a more satisfying read."
Of course, she's talking about an individual character's GMC elements. But I can see where those also play into the subplots and other narrative lines, cross-connecting my characters to create an intriguing tapestry.
Currently reading: The Sign of the Book by John Dunning. My first of his, and I'm liking it quite well.
Obviously, still working my way through Breakout and GMC.
It's all better with friends.