When Linda is writing she thinks in terms of progress and impediment.
One difference between YA and MG: YA has more impediment than middle grade.
Linda never has a subplot, instead she thinks of everything as progress and impediment as they relate to internal and external quest.
Any element has to recur more than once. If an element is in a scene, it has to be important enough to show up again in the story. Nothing can pop up later in the book that solves some problem.