No kidding. Just in my Duster schematics there are many common sources of battery. Recently I had quite a time with a blown fuseable link that took way too long to find due to me not paying attention to the original problem and assuming that I was correct in the direction I took.
And, you're right, a high majority of problems can be found in the older corroded connections in the bulkhead connectors.
When I restored my car I stripped it down to bare metal shell and had it painted. With your experience in automotive wiring you know what a pain it was with all the grounds that I connected on the body due to painting the car. It was a real education in properly grounding a cars wiring system. When you build a new engine and paint it, be sure to properly sand all the grounding points on the engine to bare metal or you will experience some grounding problems on the few ground connections needed on your engine.