The main goal of a PKM system is to store ideas and concepts for future reference, but not everything is worth storing into it. If you were to store everything you came across, you'd spend most of your day just writing things down instead of getting anything done. How do you know what is valuable enough to store? Some quick heuristics might be: - Frequency: Have you needed to search for this piece of information before? - Like an LRU cache, if you've needed it before, you'll probably need it again. Cache it into your PKM - Relevance: Is this idea something of particular relevance to you? Is it important? - Think of things that have stuck with you, ideas that have weight should definitely be stored into your PKM and serve as good references for other ideas. Those typically are the most foundational. - Speed: Use your second brain as a cache - Anything that you may need to quickly refer to add it in so that it lives where your other ideas already live.