Spaced repetition systems. Who needs 'em?
Think about the rationale behind them. They are to remind you of words or phrases (sometimes even whole sentences) of what you want to learn, right?
So why do people need reminding?
Because otherwise it would take too long before they encounter those words again, by which time they will have largely forgotten them.
So SRS are good then, right? They serve a useful function.
But here's the thing: why would too much time elapse? It's because most people do too little. They process too little language.
So what happens if they do the opposite. What if they get mega-dose exposure? They'd come across the words more frequently. Especially the most frequently used words i.e. the most useful. The ones that are worth internalizing.
Therefore, if you do enough reading and listening (or ListenReading) then there's no need for an SRS.
A spaced repetition system helps you to review items on a list in random order according to how familiar you are with them. If you know them well, they pop up less frequently. If you are having trouble with them, you encounter them more often.
Anki is possibly the most well-known SRS online. I've experimented with it.
Currently, I use a site called kanji koohii to review kanji for my Japanese.
Nevertheless, I'm not going to recommend spaced repetition systems unreservedly for three reasons.
First, they can put you under some stress.
Second, they encourage the review of isolated words (though to be fair your learning list need not consist of single words).
Third, they are non-selective as to the importance of the elements that you review (unless you are very careful in choosing which items to include).
To me, it makes more sense to read a book in your target language, because words and structures come up naturally as often as they are important.
