I basically live in my notes all day. I have two main categories:
1. General knowledge: Anything I want to be able to look up again, for me mainly how to do certain tasks in software, which is things like keyboard bindings, steps to achieve a result (e.g., something like "remove the background from a photo"), and flags for a command line program. I also add more abstract things, like computer science, and music theory concepts, but I find these concepts are usually easier to recall from memory once you know them (I've read before that memory works like a web, so if you're attaching new concepts to existing concepts, they'll be easier to remember), so I don't have many notes like that.
2. Projects: Tasks related to a project, and things I've learned along the way. For example, if I'm diagnosing a bug, maybe I found an important code snippet, so I'll cut and paste it to the project file. Also useful commands, e.g., if there's a single test I'm working on, I'll save the command to run just that test in isolation.
The general principle here is I usually find it easy to remember if I've ever done something before, but hard to remember exactly how to do it. (Research indicates that if something doesn't fit into the web, then if you don't do it enough, you won't remember it, so the notes compensate for that.)
I find this helps me stay in flow because just looking something up quickly from my notes is much less disruptive than searching to find it again (or trying to think to reconstruct it). If you don't mind searching again later for something you know you once figured out, you probably don't need notes, but if that drives you crazy, like it does for me, than notes are helpful. For me, it feels like I'm constantly expanding the number of things I can do easily without having to depend on my memory, which I know from experience is fallible for these tasks.
It's similar for context switching between projects, when switching tasks, being able to look at your note for a project, and being able to see both exactly where you left off, and documentation of everything you've learned so far, makes it easier to move forward again.
1. General knowledge: Anything I want to be able to look up again, for me mainly how to do certain tasks in software, which is things like keyboard bindings, steps to achieve a result (e.g., something like "remove the background from a photo"), and flags for a command line program. I also add more abstract things, like computer science, and music theory concepts, but I find these concepts are usually easier to recall from memory once you know them (I've read before that memory works like a web, so if you're attaching new concepts to existing concepts, they'll be easier to remember), so I don't have many notes like that.
2. Projects: Tasks related to a project, and things I've learned along the way. For example, if I'm diagnosing a bug, maybe I found an important code snippet, so I'll cut and paste it to the project file. Also useful commands, e.g., if there's a single test I'm working on, I'll save the command to run just that test in isolation.
The general principle here is I usually find it easy to remember if I've ever done something before, but hard to remember exactly how to do it. (Research indicates that if something doesn't fit into the web, then if you don't do it enough, you won't remember it, so the notes compensate for that.)
I find this helps me stay in flow because just looking something up quickly from my notes is much less disruptive than searching to find it again (or trying to think to reconstruct it). If you don't mind searching again later for something you know you once figured out, you probably don't need notes, but if that drives you crazy, like it does for me, than notes are helpful. For me, it feels like I'm constantly expanding the number of things I can do easily without having to depend on my memory, which I know from experience is fallible for these tasks.
It's similar for context switching between projects, when switching tasks, being able to look at your note for a project, and being able to see both exactly where you left off, and documentation of everything you've learned so far, makes it easier to move forward again.