Interesting article, but not without opportunities for conversation or even outright disagreement.
Just my first example:
"With normal engine wear rates, used oil metals increase linearly with an increase in miles. In doubling the normal oil drain from 16,000 to 32,000 miles, the used oil metals increase as shown in Figure 3. Abnormal wear results in a rapid increase above the linear line indicating a problem." That's not always true. Wear rates decline with OCI duration, up to some certain point. The metals increase isn't always linear. They completely ignore the topic of normal variation (a topic I wrote about; published in the same journal many years later). Further, they state it's a "problem" to see an increase of metals; that, too, is an over-stated position. Just because wear ticks up, does not make it a "problem"; it is just a marker to start paying closer attention. Condemnation limits should be set and adhered to; set only after careful consideration and consultation. Just because Fe might uptick slightly, does not mean there's a "problem" ...
There are plenty of examples of OTR rigs that run 100k miles or more successfully, using a multi-tier approach to full lube system management (UOAs, PCs, prognostics, etc). Running extended OCIs isn't inherently dangerous IF one knows what data to collent and how to interpret the results. What I would agree to is the fact that blindly running longer OCIs with no ability to understand the data won't end well for your engine. If there's a "problem" here, it's that the article takes a one-size-fits-all approach to the topic of OCI extension.