I have only ever seen one head where there was a cam bearing issue. On that one the rearmost journal and bearing *were* pretty well whacked, but my suspicion is that that was an anomaly, caused by something that wasn't the head's fault, since the rest of the head and motor showed plenty of signs of abuse. I don't know the story of what happened to that motor before I saw it, so this is speculation.
It did gall pretty badly, but I consider this to be an exception, and I have never seen or heard a *documented* story of another one like it. I haven't ever seen anything that made me suspect an inherent flaw in the design of the oil supply system to the valvetrain. I think that myth probably originated from broken cams caused by balancer bolt loosening up, and then people assuming the breakage was caused by the cam seizing...
Remedy is to just drive it and not worry. Synthetic oil is a good idea too, but not for this reason. If you can spare some extra money and effort, head studs and a fresh radiator are good places to spend it.
