I'm doing something similar with my German right now. Not sure if 115 days can be considered a sprint, though it certainly was a sprint for the first 90 days.
I spent all my time reading, and accumulated 20 thousand words. Those are words that I know passively and can recognize in text with some mental effort.
I truly consider it a success, after first 3 months I can watch german youtube and what is the most important - find it interesting. I only get a gist, some words here and there, but it is enough to keep me involved. Once youtube videos are comprehensible, I'll be progressing slowly but surely, as it was with English.
As for 1-2 week sprints - I believe it is a good idea as long as you continue learning in between. I think about a language acquisition as of a marathon - you can run some sections quicker if you feel like it, but what you should never do - is to stop.
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Wow, that first 90-days sprint of yours was really intense! Do you care elaborating on how you set it up? Was it just reading or did you supplement with textbooks, anki, and so on?
What about listening comprehension? For me it is the hardest skill to acquire, so I find myself at a point where I can read comfortably but still can't understand any real native audio. The fact that after 3 months you could not only read, but also get at least the gist of youtube videos is what I find most impressive.September 17 at 09:50
I used LingQ almost exclusively at first. I read and listen following the text, a few times, then listen a few more times during commute or wherever. After a while it became easier and now I listen to the lesson audio 2-3 times at most. Right now I'm mostly watching youtube in German and do the minimum in LingQ to keep my insane streak.
Comprehension really depends on what experience you have. For example I was going to buy a new phone, and therefore I was quite interested in all the reviews and so. After translating and watching several of those I could understand this type of videos quite well. At such a moments it felt like being at the much more advanced level. This feeling evaporates quickly once I go to unfamiliar topics))
To conclude, I'd say that sprints and hard work make sense mostly at the beginning stages of language learning. Later, to become truly fluent you'll have to spend years no matter what.September 17 at 11:32
Watching YT videos that I got the gist of and found interesting is exactly how I have been developing my listening comprehension. Hours and hours and hours, not of study, but of entertainment of a huge variety. All while continuing reading and building vocabulary. I used to be tickled when I could sort of understand. Now I'm ticked when I don't fully understand.September 17 at 14:39