I find the absolute opposite to be true- At the time of the lecture or meeting or whatever, I am just trying to capture everything. What is truly important and what is noise is not clear to me at that point. Also in the beginning stages of a class or project certain concepts or decisions seem very new or foreign, and a few months later they are deeply ingrained and no more likely to be forgotten than understanding what gravity is.
By far the most successful study technique I have ever used is recopying my initial notes. The second set is much more coherent, organized, and focused on the tricky bits while removing things that I thought might be important at the time but ended up not being important.
I think someone did you a major disservice 30 years ago.
I'm not sure how I would achieve it though? The right initial structure isn't usually clear at the beginning of a conversation/research session/whatever I am taking notes on.
Helps me clear my mind, and it saves me a lot of time in the morning, because I can start work and have some wins for the day within 15 minutes...and that momentum carries me through....
Also, the shut-down period is nice, because when I'm tired at the end of the day, it doesn't take a lot of energy.
I also put references to my (page-numbered) paper notebooks in my notes file, and vice versa, so stuff that would be very long to transcribe doesn't usually have to be transcribed at all.
I also have a pretty strong aversion to headless-chicken-mode, having seen it as a pathological disaster spiral at a couple of places where everything is urgent all the time, and so you never have time for anything. Being in too much of a rush to do things properly is a trap.
I find as an employee I have to fill and empty my head a lot. I have a good short-term memory, but things that I don't write down tend to slip out after a week or two. "Oh, I worked on that thing? I don't remember that."