I don't know your specifics, so I'm going to reply with what I've learned about learning:
I found reading a textbook, and typing notes into a dumb markdown file with the textbooks name is good enough. Typically: definitions, quotes, and personal thoughts while reading. Did this for stats/comp sci/etc. Obsidian + markdown worked for that, even without plugins. Being able to text search is useful, which is why I don't hand write.
Anything beyond that you have to be cautious about paralyzing yourself from trying XYZ PKM.
Theres a quote from stephen king that goes somewhere along the lines of "during first draft don't try referencing or fixing grammar because it breaks your train of thought". I think similarly, when learning something, choose the thing thats most out of the way (usually the simplest) that is least likely to break your train of thought.
In terms of tracking how much you're learning, I'd be very very slow and incremental in what tooling/methods you pick. For me, I just trust myself after reading/notetaking a textbook. Usually homeworks get very easy which is a good sign. Being able to explain what I learned to someone else is a good sign.
Great advice, thanks!
> Usually homeworks get very easy which is a good sign
I agree, but having homeworks in itself is a big advantage! It means you're in a structured learning environment where someone has taken the care to create a learning path and added checkpoints with carefully designed problems designed to refresh + assess what you've absorbed until that point.
When you're learning outside the classroom (for yourself or on the job), there's this sudden loss of all bounds where you now also have to draw a line of what knowledge is reasonable to acquire and what is out of scope. For example, when working independently on personal projects, I sometimes get sucked into reading about the details of protocols, standards, RFCs etc. and have a difficult time deciding when to stop.
One answer is learn just enough to solve the problem at hand at move on, but if you're in a field like eg. security you feel an obligation to do your due diligence when designing something. And of course, with LLMs now it's possible to move past any problem without learning anything at all, so you have to be even more intentional in which things you do decide to learn.
I would add that writing down your reactions to the books and not the book content itself is helpful. If something reminds you of something else then write about that. I mostly throw away all these things as the point is just to write them not to read them back