Well, like you, I’m not at a fluent level, probably nowhere close if I’m honest, but the few breakthroughs I have had, have come from seemingly nowhere.
I agree there is some kind of strangeness going on in the brain that we’re unaware of. I’d almost liken it to “being in the zone” in sport where for reasons unknown to the player they suddenly can’t do anything wrong, they see a tennis ball like a football, golfers who feel like they could hit fairway after fairway with their eyes closed, or the runner who just can’t stop making new PBs etc.
On the other hand, it’s not quite like that, in that being in the zone doesn’t usually last, lol, but it seems to appear like magic.
I’m not one of these people who believe that we only use 10% of the brain or whatever nonsense they say, in fact the brain uses so much energy that it’d be impossible to get it to do much more than it currently does, but I do think there are natural processes, at an unconscious level, that sorts out language learning for us.
Steve has said before that when he comes back to a language, after a break, he’s often better than he was when he left it. I’ve found the same thing (at my very rudimentary level), something behind the scenes is definitely going on if you ask me.
If you look at everyone around the world - almost without exception - we learn our native language at close to identical rates, some will lag a few months, some will be early speakers, but by the age of around 5-6 we are all very tuned into our language and can even speak it with decent grammar, if we have a healthy brain, and we’re exposed for this period, you probably couldn’t find a single child (from a sample size of billions) at that age who didn’t understand and speak the language.
I don’t believe this ability deserts us when we reach adulthood, what deserts us is that perfect environment of 24/7 immersion, with at least one (often 2) native tutors (parents), as well as siblings, other family members, not to mention zero interference from years of another language imprinted on our brain, add in the fierce survival instinct we have at that age (motivation). We never get that environment again in our lives. You can try to create something similar, but i don’t think it will come close to what we had before. Furthermore, not a single person alive remembers how they did it!
I wonder how good one would become if you took a 40 year old out of their current language environment, put him into a new one, and repeated the exact same process again in that new language, I wonder how long it would take that person to equal his native ability, or even surpass it? Another 40 years? 100 years? 200 years? Would they acquire a native accent in such a time? Would they totally forget their original language? After 200 years, would there be any trace left of their native tongue? Perhaps they would never lose their accent? I do think they would use the 2nd language at least equally as well as their 1st though.