To study my novel, I lay the cards out in columns by chapter. Our kitchen table is big enough to hold eleven chapters (approximately 1/3 of the novel) which is a reasonable amount to study at one time. The cards allow me to see what will happen if I move scenes around. I also added colored post-it notes. The yellow ones relate to problems that I noticed while making the outline. The blue ones suggest modifications that will be necessary if I leave the scenes in their original order, but change a major premise in the plot.
Novels, especially in early drafts, are long, unwieldy things. The cards let me subdivide the problem and compare possible solutions.