Measuring from memory - an impossible project?

What I am currently experimenting with, and I don't know if it makes sense or could be recommendated, is measuring from memory.
The set-up: I have this site here open, and some youtube-video, usually some music video with boring visuals, like a concert or something.
I start a figure drawing, look at the figure for a few seconds, but before I start drawing, I switch to the youtube-clip, so I can't see the reference any longer, then I try to draw what I remember.
Initial comfort level 1 out of 10, can't recommend, feels about as pleasant as intentionally hitting a wall with your head repeatedly, while chewing on glass..
I spent quite some amount of time learning how to measure from a reference, but there is always the risk of getting lost in detail  Now I expect myself to be able to draw at a certain halfway consistent quality from a reference, and the outcomes I produce with this method are naturally abysmal and disappointing without end.
On the upside, once I am done drawing the few lines, that I can remember, I can still switch back to the reference and compare results. And the comparison does give me a lot of feedback about my methods of measurement. For the sake of clarity, with measurement I mean about the widest range of techniques possible. Learning how to draw an abstract paperdoll of a human body absolutely is just one more method of measurement, like is getting known to tyoical proportions, and I guess this way of "measuring from memory" doesn't even make sense without some of those available.

What I hope to achieve with the attempt is to one day just go to a park and draw from people, that are actually moving around, and still capture the scene, without either having to first unalive them to make them hold still, or at least having to take a photo, and then using my bad photo as the reference instead of the sight before me.

It is quite a hard check against trying to include too much detail. It's just astonishing how hard it is to even remember faintly the positions of the main masses or major limbs after staring at a reference for a few seconds, although in my mind, before I start drawing, I feel like I remember all of it perfectly. Then the pen hits the paper, and all of that confidence bursts away in a heartbeat once I cut myself off the physical reference and rely on the clarity of the "reference" in my memory.

I think this feedback has impact on what I draw when I draw olschool with the reference "on", as I get refocused on essentials over details. I generally dislike the terms "flow" and "stiffness", because they are usually highly ambiguous, lead to a metric ton of misunderstanding and make beginners just attempt dumb stuff to produce "better flow". But I think the question of essential versus detail is valuable.

Like, it is the undeniable quality of each poem ever, that it is astonishingly easy to remember, given the length and complexity of the text, as poems are in essence a mnemonic device developed by pre-literate cultures. Making visual art "stick" to memory is dependent on creating mnemonic techniques, and I think lot of the misguided talk about "flow" and "stiffness" is really aimed at achieving that.