Takes a lot of effort to commit my notes from a book into my head, but a tiny amount of resources to store them on my computer.
>The most difficult task, beyond that of just persisting until the benefits become clear, is deciding what’s valuable enough to add in. In a 3 year period, one can expect to spend “30–40 seconds” on any given item. The long run theoretical predictions are a little hairier. Given a single item, the formula for daily time spent on it is Time = 1⁄500 × nthYear−1.5 + 1⁄30000. During our 20th year, we would spend t = 1⁄500 × 20−1.5 + 1⁄3000, or 3.557e-4 minutes a day. This is the average daily time, so to recover the annual time spent, we simply multiply by 365. Suppose we were interested in how much time a flashcard would cost us over 20 years. The average daily time changes every year (the graph looks like an exponential decay, remember), so we have to run the formula for each year and sum them all; in Haskell:
sum $ map (\year -> ((1/500 * year**(-(1.5))) + 1/30000) * 365.25) [1..20]
# 1.8291
Another good use case is country flags, because you can't easily look those up (other than pulling up an image of ALL the country flags)
1) test word -> meaning, not word -> word in other language
2) I don't test reverse most of the time, unless I really want to remember how to say something - output tends to emerge by itself given enough input
3) When a word has multiple meanings I add context (usually a related word or colocation as a hint - whole sentences can cause you to associate the sentence with the word but not recall it in other situations). Words with lots of meanings (in Japanese I guess that would be stuff like 引く or in English 'run'?) tend to be very common words so you don't need to use flash cards so much anyway.