If its stock then its fine. That system worked for 100 of thousands of cars. Add a relay circuit for the headlights. Why? because the original lamps were rated 40/40 Watt. Since the 70s replacements draw more. Bonus of using a relay harness is that reduces the maximum possible load through the R6 wire by 9 amps. I'd say the biggest issues are condition of wires and connectors. That most certainly includes the quality of the repair and replacement work. It also includes good wire routing and support. I, like many others, didn't give those last two much respect as young shade tree mechanic. But thats a big part of why wires and junctions survive long use without damage.