If you're going to be reviewing for 30 minutes a day, then I generally advise setting your New Cards/Day count to 30. Your goal is then to supply yourself with enough new cards so that you don't run out. For some languages, that means 15 words (2 cards per word). For other languages, that may mean fewer words. The Japanese model decks, for instance, can spit out around 10 cards per word if you're really digging into creating mnemonics for your radicals, Kanji signatures, stroke order cards for writing Kanji, etc. So 3 words/day might be plenty, there, if learning to write in Kanji is something you want.

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