Regarding the lack of detail, this has to be taken in a bit of context. Howard Oakley -- the author of the site -- has many articles that go into great technical depth and ones that are more high level advice.

While I would agree the article should link to more details, they are easy to find on the site. In fact, the author has written many benchmarking tools. Here are their tools related to disk and file system performance:

https://eclecticlight.co/dintch/

It is a fair bet, they used their own benchmark tools. You can read other articles on the site that describe their work.