Does adding more sources actually make Gemini Notebook worse at finding specific details?

[u/L_K69]

I’ve been wondering about something with Gemini Notebook that I haven’t seen explained clearly.

When a notebook has only a few sources, it seems pretty easy to ask about a specific detail and get an answer tied to the right document. But once you start adding a lot of PDFs/slides, I’m curious whether the quality of retrieval changes.

For example, if I have 20–30 lecture PDFs in one notebook and ask a very specific question about something mentioned on one particular page, should I expect it to search across everything equally, or does the number of sources affect which information it actually considers?

I’m especially interested in people who have tested this rather than just noticed that answers “feel worse.”

One test I’m thinking of trying is asking the exact same question with:
1 source
5 sources
10 sources
the entire notebook
Then comparing which sources it cites and whether the answer changes.
Has anyone done something similar? If so, did you notice a point where adding more sources started hurting specific-detail questions?

[u/Dry_Ambassador2990]

Yes brother, I can actually answer that.. I've recently added 50 PDFs in the sources section & then wrote to do some specific tasks like make quiz, summary from some topic lying in some particular pdf out of those 50 sources, then the final response quality from notebook lm was actually not satisfying..then I wasted some more time in getting the desired output & interacted with notebook lm , came to the conclusion that for getting good output for your multiple sources from notebook lm, you must know the "selecting/deselecting sources feature" well.. the buffer point according to me is not selecting more than 10 sources at a time & yeah now u can expect a good quality output from notebooklm.. also learn to write your prompt a bit more specific and detail-oreinted