I agree that a known engine, broken in, and running well should not need testing, so to speak. But those tests can reveal air filter problems and coolant issues also.
Regarding air filter (silicon) contamination... some oils contain silicon (mobil1) and cause false positives. If you WANT to test, maybe call blackstone and ask what oils they recommend to not interfere with testing.
I pull samples about every 2 years in my daily drivers, and after engine work in my sports car.
The tests more than paid for themselves due to cutting WAY back on changes in my daily driver (from 3k to 12-15k changes). Even after 12-15k my
oil is still WELL within spec on the additive package and contaminants are the same as they are at 3k miles.