I brought up warranties because that's one of the primary concerns of automakers and oil companies. Automakers have to foot the bill if customers are following the maintenance rules and things sludge or blow up. Oil companies have to foot the bill if their oils aren't up to claimed certifications. Automakers do not tend to set up OCIs to save their consumers a bunch of money. Granted, some factory OCIs have been optimistic. But, the OEMs usually have a very good idea how long oil can last in an engine when they introduce it into the market. And, if they're mistaken, they want that corrected in a hurry.
Dave Newton decidedly does NOT need Blackstone's comments to determine whether or not lubricant numbers fall within norms for an engine family. And, when extending OCIs, UOAs are the primary tool, since that's what they're for. Assuming contaminants aren't above certain condemnation levels, fuel dilution is under control, viscosity is within norms, and reserve alkalinity remains, the lubricant is suitable for continued use.
I was running taxis on conventional at double the OEM's recommended OCI for many years. Every one of them went hundreds of thousands of miles. Other posters here run fleets. Others also run fleets and do tear downs and UOAs and extend OCIs to extreme levels, and they put their money where their mouths are.
