What it does well
- Grounded, cited answers from the sources you give it. This is the right architecture and most tools don't have it.
- Large volumes of source material handled at once.
- It's free, which is not a small thing when you're a student.
- Good at synthesis — pulling a thread across several documents at once.
The half it doesn't do
NotebookLM answers questions about your sources. That is comprehension — and comprehension is not what you're graded on. You're graded on retrieval: producing the right thing, unaided, under time pressure, weeks later.
Those are different capacities. Reading a beautifully-cited summary of your notes trains the first and does almost nothing for the second — it's the fluency illusion with citations attached, which makes it more convincing, not less.
The machinery that produces grades is the boring, uncomfortable loop: being tested, failing, being re-tested on exactly what you failed, at the moment you were about to forget it. That means quizzes graded against a rubric and flashcards on a real scheduler, and NotebookLM has neither.