With the influx of recent NYT articles on education I'm nearly convinced the NYT is purposely trying to sabotage education (or rather they have a clear agenda, which I wish I knew where came from, that they are pushing through by twisting other people's words).
As you say, retrieval practice is absolutely fundamental. Every person does it! Studying doesn't comprise of one method - concept mapping or repeated study - it's a combination! What kind of ridiculous study was this? Also, the article makes it seem like all experts purport 'concept mapping' as the "holy grail" of learning, that's it, nothing more.
The test obviously assisted by assisting in organizing and structuring the information for them, in addition to highlighting key points from the readings. Also, the article never mentions what type of test they were taking. Multiple-choice? Essay? Short answer? Verbal? None of the above? That information would be the single most important piece of this article.
To me this article seems to simply highlight how poor students are at understanding how they themselves learn and think.
What NYT seems to want you to think: Test taking is the best way to learn. Forget in depth studying techniques or figuring out how you yourself learn.
More of the truth: Tests (depending on how they are set up) are useful in assisting with learning in various ways, and super useful in providing feedback and assessing where a student is and what to focus on in the future.