I'm definitely not fluent in Japanese. But please don't get me wrong, I wasn't trying to say to start putting words together, without any knowledge of grammar or so. But we are talking about learning 10K sentences, which is just unnecessary, and ineffective.
I'm sensing that what you are trying to say is to be PERFECT Japanese, but note, that is not = fluency, that's beyond that (by far). Why would I want to be perfect in any language? Not even it's almost impossible to achieve (specially with Japanese) but ineffective, because the learning curve will go up exponentially with every added percentile to your knowledge, beyond 85%-90% and so.
If you learn the words with some grammar (emphasis is always on the words), and start putting them together, you will eventually catch up. I don't see how this can hinder learning certain fixed expressions along the way.
But if you ONLY learn whole sentences + grammar you might find it difficult to express yourself the way you want - thus limiting your own "freedom" in the language, hence less fluency.
You have to understand that the brain works by association, the more connections you have the more you know (and can know). I believe that having 10K words memorized will still give you much more connections than learning 10K fixed sentences.
Also Japanese is just a language just like any other, no need to mystify it too much imo.
I'm sensing that what you are trying to say is to be PERFECT Japanese, but note, that is not = fluency, that's beyond that (by far). Why would I want to be perfect in any language? Not even it's almost impossible to achieve (specially with Japanese) but ineffective, because the learning curve will go up exponentially with every added percentile to your knowledge, beyond 85%-90% and so.
If you learn the words with some grammar (emphasis is always on the words), and start putting them together, you will eventually catch up. I don't see how this can hinder learning certain fixed expressions along the way.
But if you ONLY learn whole sentences + grammar you might find it difficult to express yourself the way you want - thus limiting your own "freedom" in the language, hence less fluency.
You have to understand that the brain works by association, the more connections you have the more you know (and can know). I believe that having 10K words memorized will still give you much more connections than learning 10K fixed sentences.
Also Japanese is just a language just like any other, no need to mystify it too much imo.


