>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:
>Which evaluates to 1.8 minutes. (This may seem too small, but one doesn’t spend much time in the first year and the time drops off quickly55.) Anki user muflax’s statistics put his per-card time at 71s, for example. But maybe Piotr Woźniak was being optimistic or we’re bad at writing flashcards, so we’ll double it to 5 minutes. That’s our key rule of thumb that lets us decide what to learn and what to forget: if, over your lifetime, you will spend more than 5 minutes looking something up or will lose more than 5 minutes as a result of not knowing something, then it’s worthwhile to memorize it with spaced repetition. 5 minutes is the line that divides trivia from useful data.56
I have definitely wasted lots of time creating and reviewing cards for words that I never see again (the long tail) or don't strictly need to know. But the feeling of coming across a word that you learned and -knowing- it is amazing. It also helps if you enjoy the process of creating and reviewing cards - tending to your knowledge garden, so to speak.
>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:
>Which evaluates to 1.8 minutes. (This may seem too small, but one doesn’t spend much time in the first year and the time drops off quickly55.) Anki user muflax’s statistics put his per-card time at 71s, for example. But maybe Piotr Woźniak was being optimistic or we’re bad at writing flashcards, so we’ll double it to 5 minutes. That’s our key rule of thumb that lets us decide what to learn and what to forget: if, over your lifetime, you will spend more than 5 minutes looking something up or will lose more than 5 minutes as a result of not knowing something, then it’s worthwhile to memorize it with spaced repetition. 5 minutes is the line that divides trivia from useful data.56[1] https://gwern.net/spaced-repetition