[bluquark]

Personally, as an intermediate Japanese learner, I have been careful to choose the right input just as Krashen advocates, but I also find Anki indispensable. I found to my surprise that I have been improving about equally quickly using Anki+Animebook+Yomichan for 1-2 hours a day while living the US as I did during an earlier period when I was living in Japan (but without access to computerized methods beyond a basic pocket e-dict).

As a beginner, appropriate input was enough to care of "spaced repetition" on its own, since children's media constantly rotates over the same small set of vocabulary. But after I improved past the ~2000 most common words or so, it happened more and more that a word I recently learned didn't appear again in my input until it had already been flushed. The probability that I would actually learn a new word for good progressively decreased as I picked the lower-hanging fruit, which is the cause of the dreaded "intermediate plateau".

I gather Anki pushes out the plateau much further: I have heard that it starts to feel Sisyphean to learn new words with it around the 15000-20000 word mark instead.