You should construct evergreen (permanent) notes based on concepts, not related to a source (e.g. a book) or an author.

Your mental models are compression functions. You make them more powerful by trying to use them on new information. Are you able to compress the new information with an already acquired function? Yes, then you've discovered an analogous concept across two different sources. Sort of? Then maybe there's an important difference, or maybe it's a clue that your compression function needs updating. And finally, no? Then perhaps this is an indication that you need to construct a new mental model – a new compression function.