Interesting discussion. Here is my experience. Anecdotal data a n of 1.
I was sailing my CS36 Merlin on Lake Ontario, about seven miles offshore headed back to Toronto. Keel stepped mast, mast shoe bonded to Hydrokeel wing keel (lead) with large guage wire connected to shoe and a keel bolt. Through hulls are not bonded. All bronze.
Saw really bad (worse I've seen) electrical storm approaching. When lightning struck the water ahead on my port bow, then starboard bow, started motor, put handheld vhf in my foul weather gear pocket, got position from GPS, wrote it on a piece of paper and tucked that in my pocket too. Wind died, torrential rain.
BANG! I remember a sizzling sound, that was all my masthead stuff hitting the water just behind me. Guess it was red hot. Autopilot failed. Put on wheel brake and took hands off wheel. Called Canadian Coast Guard on handheld, reported position and having been struck, said I was going down below to check for damage and would report back in ten minutes. They said they would call SAR in Trenton and if I did not report back they would be out.
Checked boat for water. None. All instruments out, lights out, vhf out, alternator shot (no engine instruments). Some led's on electrical panel out. Oddly enough the Garmin GPS (a small Garmin 64?, not grounded) was still working. Called CG, reported situation, said I was continuing to Toronto (about 70 miles more) and would report every half hour but turning off handheld to conserve battery. They informed me that SAR had told them that damage might not be readily apparent such as keel bolts failing. I said thanks.
If I did not report every half hour SAR would be out. We went another hour through the electrical storm, making slight corrections to the course but with wheel brake on and hands off. Got back to Toronto. Thanked CG.
Hauled the boat a day or two later. There was "treeing" (electrical burn marks in a very unique pattern) at every through hull and on the rudder at the gudgeon. The charge had gone throughout the boat. From stem to stern. No structural damage. Mast was pulled. Headsail showed slight burning at the foil. The headsail was a North with a zippered sleeve over the foil. (Sometimes the foil sections fuse together).
Replaced all instruments, alternator. Corrected magnetic compass. About $20K.