As you have clearly found, there are some wildly varying oppinions out there. On my '70 woodie, i identified wood burn around shaft logs, and a few areas of the bonding system itself. I read all the contrasting oppinions and decided not to risk pulling the bonding. Instead, I took the areas of worst burn and cleaned, and cpes impregnated them. I check regularly and have not seen and recurrence over 18 months. That being said, obviously the burn came from somewhere and the above wont have changed that. I believe this burning happened over a long time in "never inspected" parts of the boat. At last haul, no burning was found on the outside. I removed a zinc or two as i suspect previous owners were a little over enthusiastic there. I was also advised (but have not yet completed) to measure the current flow in the boat. Effectively you are lookkng for electrical leaks into the boat, bonding, water etc. Certainly i had some terrible wiring when i got her that has since been addressed. I know for sure the 12v cabin lighting was grounding occasionally.
Hopefully this non scientific but first hand experience helps you somewhat!