It's possible, and very effective if you want to save time, but it comes at a (very slight) hit to actual muscle growth, since it's likely you'll end up limited by your cardio as opposed to the muscles themselves. If your goal is to build muscle, a set brought to failure by anything other than the target muscle is ineffective.

You're describing supersets.

Remember that it’s your brain driving the coordinated electrical signals (and maintaining steadily increasing strength of those signals) which makes the muscles do the work.

Your brain needs recovery time.

This seems sarcastic or wildly inaccurate.

To clarify, two things.

The brain does not directly drive the muscles. It does not have copper running to them, providing a charge. Instead, cell after cell transmits the signal, from brain to muscle, each cell providing its own charge. The brain expends more energy thinking about abstract ideas, than telling a muscle to move.

Second thing, healthy, fit people run for hours, bike for hours, without issue. As a teenager, I'd work on a farm for 10 hours, picking fruit, throwing bales of hay, digging, on and on without tire.

Yet just continually walking, uses more "brain telling muscles what to do", than any single heavy lift plus even perhaps 10 seconds of break.

Realistically, writing cursive with a pen, typing fast, should use as much brain energy, for fine, detailed control requires many different muscles all being used at once, hence more signaling.

It's not really, central nervous system exhaustion needs to be managed with strength training. And it takes quite a bit of concentration to lift properly, a short mental break is really useful.

I added more details while you were writing this I think.

Your nerves don't care how heavy something is. Fine muscle control is just as intensive as anything to the nerves. Talking uses waaaay more nerve and muscle control than lifting heavy weight.

Breaks are required so that the blood can carry away waste, and replenish glucose and oxygen. That's all.

The point is that the brain is the essential point of initiation of muscle movement, and it is an essential part of the sensory feedback loop which then leads to muscular adjustments.

The ability to focus without fail is not unlimited. When you're holding more than your bodyweight on your shoulders, the demands to simply maintain balance are significant. This means a lot more than just muscles holding a static position. If you are not very focused on the sensations which indicate a change in balance somewhere, you will lose form and possibly hurt yourself.

Whatever the mechanism within the brain, the breaks are also necessary there. Of course the muscles need recovery time, but the brain does also.

I'm someone who's been seriously active in powerlifting for years and I was getting ready to argue, but you seem to be correct. Not only was I not able to find research supporting CNS fatigue, Menno Henselmans himself(quoted in the article) agrees https://mennohenselmans.com/cns-fatigue/.

What I have anecdotally observed is that regularly lifting closely to your maximum (particularly at higher levels) will inevitably lead to accumulated fatigue. Whatever the root cause of that fatigue is (whether muscoskeletal, endocrine or nervous) is a factor that does lead to degraded performance over time.

The literature is lacking in longer-term studies, so I'm curious to see whether my anecdotal experience is pure confirmation bias or there is a mechanism behind it.

I don't think it seems to be that clear cut, but the consensus does seem to show it's not a huge driver. More anecdotally though, to my original point, I really do need some brain rest in addition to just muscle fatigue between hard lifts.

Fine motor skills are, afaik, controlled by different networks than gross motor skills. They develop at different times in the brains. I don't think they can be that directly compared. Besides, I do like to take a break if I'm typing or writing a lot :)