The bumpers should be arranged in a square or rectangular pattern on the back of the wall hanging under the sawtooth hanger. We also arrange 4 glue dots on the back to hold the art to the cardboard backboard and the location of each glue dot serves as a guide as to where to place each bumper. The glue dots sometimes leave sticky residue behind, so putting the bumpers in the same spot covers up the stickiness.
If you choose to make your own square or rectangular pattern instead of choosing where the glue dots were placed, I would recommend each wall bumper be at least 2” apart.
The additional “island” piece for VA is too small to put a sawtooth hanger or bumpers, so it has adhesive tape on it.