Nothing beats "inheriting" other people's problems and being the one left to sort them out.

Over the past year I've found myself in this situation several times. Whether it was the wiring in the bathroom or yesterday's discovery of how the wiring in the kitchen was done. The entire floor is served by two circuit breakers — one for the lighting circuit (16A) and one for the sockets (16A). A single lighting circuit you could almost understand. But a single socket circuit — no! If you ever find yourself redoing your electrical installation, plumbing... the best solution is to rip everything out and do it again from scratch, properly!