NotebookLM builds its answers around the material in your notebook and can show references to the sources. This gives you a useful way to check how an answer relates to the original.
The same habit is useful in other AI tools that show sources. A link needs to support the claim beside it. Merely discussing roughly the same subject is not enough.
You do not need to investigate every everyday idea as though it were a research project. Start with things that affect a decision or that you plan to share. A quick check can improve both your understanding and your next question.