This time, about four years. I studied it in college over twenty years ago for five semesters, and I’d retained basic (-masu/desu) conjugations and about 50–100 kanji, but my vocabulary had deteriorated a lot — I retained very few words I hadn’t learned the kanji for, basically just functional words like たくさん and もう. (I also had no opportunities to keep up practice since other commitments required I keep up practice at another foreign language.)
I resumed spoken and kana-based study in 2020 as a pandemic project and then I started WaniKani in late 2022 when I just got too frustrated that my access to written Japanese was so minimal. (I’m hard of hearing and need subtitles for English TV, so that just compounded the problem.)
I feel I’m in a much better place now than I was a year ago, even though the 30’s levels have been quite difficult. As you mentioned, part of the difficulty is that when you first learn a kanji some of them look very visually distinct and you can Burn say, 誰 before you find out there’s a whole family of left-right kanji with 雄、推、確、権、稚, etc. and you hadn’t been paying attention to the components.
But in the 30’s levels they start throwing you multiple kanji sharing an overall look, radical configuration and/or a reading at once, which makes you concentrate on those distinctions. This was good — but it also resulted in a few dozen resurrections when I realized I didn’t really know what 誰‘s left component was once I’d learn all those alternatives.
I also started using the WK Double-Check userscript to viciously mark wrong things like mistakes WK let slide — no, 依頼 does not mean “trust” — and cases where I felt I was still guessing at things like vowel length or when I confused homophones. (It also let me say, “I feel Master confident on this one, but I don’t feel Enlightened confident; let’s knock it back to Guru for one more try.”) It’s frustrating that I still have a couple dozen Level 1–10 items still getting knocked down all the way to Apprentice after hitting Enlightened five or six times, but I just have to keep trying.
I was a linguistics student, and so I took a lot of languages at once at uni and frequently got annoyed by elders in my classes via continuing-education programs. But now that I’m middle-aged I’m discovering that brain plasticity isn’t a myth — I have to work much harder to retain things and especially fine distinctions like 績 vs. 積 when read セキ.
Still, it’s gratifying that now — even with “just” ~1000 kanji burned — I can read a lot, and guess at even more. I can now read 少年漫画 without a magnifying glass for the furigana! And Japanese subtitles on TV shows are now more helpful than distracting. That’s a lot of progress in two years for an old dude, I think!
I was neither fish nor fowl trying placement tests into local Japanese classes and was loathe to spend hundreds of dollars on classes that were 90% below my level just to progress, but soon I’ll be able to take a beginner-intermediate class. Italki and other on-demand online tutoring is helpful too. I have a long visit to Japan planned next year and I’m just crossing my fingers I’ll get something more than 「日本語お上手ですね！」…