> What I hold on to are the core concepts that allow me to hit the ground running when I have to interact with the subject-matter again.

Exactly. And those also come with doing the thing, or watching the thing being done, or reading about the thing, or thinking about the thing. You often don't have to actively try to kastle / cram / grok / etc the information to remember it. Just being exposed to it will make you remember some of it. Knowing where to get more accurate info is often a greater skill / benefit than knowing the details yourself. Especially in fields where knowing all the details yourself is almost impossible.

Weak article.