To Suggest Depth
Overlapping creates the appearance of depth.
You know this already. And I know you know this because everybody knows this. I just thought I would remind you anyway.
Overlapping is probably the easiest way to create the illusion of depth, especially when you are appliqueing a quilt.
The horses in the design above are flat silhouettes. But because they overlap you know the black one is in front of the others. The result is not a flat image but one with depth.
For more depth combine this with a value change.