> consistent practice with a fluent speaker where ones effort is being tested in some way like children
I agree with the total time and deliberate practice aspect but in my opinion you are underestimating one extra factor for adult learning.
As an adult if you practice a new language with natives (outside the context of a formal lessons) the majority of people will be a lot more accomodating of mistakes and mispronunciation simply because of the social pressure of wanting to 'save face' and not trying to demotivate the person who is learning.
There are maybe a handful of close friends who will be brutally honest enough to correct you, in the same way they would correct an infant. For the most part as an adult it is more common that you end up practicing with an 'excessively tolerant' feedback loop from other language natives.
I agree with the total time and deliberate practice aspect but in my opinion you are underestimating one extra factor for adult learning.
As an adult if you practice a new language with natives (outside the context of a formal lessons) the majority of people will be a lot more accomodating of mistakes and mispronunciation simply because of the social pressure of wanting to 'save face' and not trying to demotivate the person who is learning.
There are maybe a handful of close friends who will be brutally honest enough to correct you, in the same way they would correct an infant. For the most part as an adult it is more common that you end up practicing with an 'excessively tolerant' feedback loop from other language natives.