Just recently watched a video on learning japanese by immersion
They say you have to do some ground work by learning the alphabets, basic grammar and some common words using SRS flash cards. Afterwards immersion is supposed to mostly fill in the gaps (you should tolerate ambiguity and let your brain figure out new words from the context). The video mentions it takes multiple hours a day for years to get good, but it also works with passive listening while doing something else. However they also talk about adding new words you hear to your SRS, mimicking what you hear, interacting with native speakers, etc so there’s definitely a lot more to it than just sitting down and listening to podcasts.
I have a 1,360 day streak of learning Japanese on DuoLingo, 5 minutes every day. I’m at the point that I can read Kindergarten books, albeit slowly. I figure another 3 years and I should be able to read manga.
A colleague of mine swears by immersion, like you mentioned. She lived in Japan for 5 years and knew none beforehand, and was more or less fluent by the time she left.
Honestly, DuoLingo is one of the slowest and shittiest ways to learn a language. I think it’s a great supplement to a language learning routine, and a nice method to keep your habits going, but it’s borderline useless by itself.
That said, it 100% depends on your personal goals. If you’re planning to go to Japan sometime in the future and would like to be able to accomplish some basic interactions (ordering food at a restaurant, asking where locations are, etc.) but have no interest in becoming fluent, it could definitely serve useful.
Honestly it’s just become part of my morning routine and helps jump start my brain for the day. Learning new things is fun even if it’s not the most strategic approach to becoming fluent in a language.