I haven’t messed with layout sketches before. I have used standard sketches in an assembly to drive parts, “top-down” modeling, but I have never used blocks in layout sketches to accomplish this. As an industrial designer my modeling approach is typically bottom-up, modeling a full product within a single part file, and breaking it up in to multiple bodies. That approach gets my head turned around if I need to deal with mechanical systems and moving parts, though, so I’d like to try to work some top-down layout sketch techniques in to my brain.
Here are a couple illustrative videos I found this morning while looking things up.