Do you have any idea how many blown head gaskets there are each year in the US?
How often does a mechanic have trouble identifying the problem correctly.
It’s probably impossible to estimate unless you have inside information from a major gasket manufacturer. But I’d guess that it’s probably far less as a percentage than people who follow this forum might suspect. We deal in problems here. A reader could probably get an idea of how large a portion of overall serious problems are constituted by blown headgaskets, but not how many headgaskets blow as a portion of the total cars on the road.
A reader of this forum could probably also get an idea of what makes and models are more prone to headgasket failure than others.
If you are able to figure out the number, I wonder how many of the number would be due to owners that kept driving with the red temperature light on or the temperature needle on H?