# Make custom study “review ahead” relative to interval

Currently, reviewing ahead means reviewing the cards that would have been due the next `x` days. In other words, to render more cards due, we reduce their current intervals by an absolute value.
For cards we have (re)learned today, and which therefore will be due tomorrow (given the default settings), that means we see them in our custom study the same day and also the next day in the regular review queue because the first interval is always one day. So in this case, we don’t even review ahead, but additionally.
But also in less extreme cases, we prefer shortening a card’s learning interval from 5 to 4 days over shortening another card’s interval from 100 to 98, just because the former card happens to be due closer to the present day.

Now, you could argue that custom studies just should be used very cautiously and sparsely. But I believe, reviewing ahead could be a great way to take advantage of the days you’re enjoying learning and reduce the workload on days you’re busy or learning is a struggle.

To fix the aforementioned problems, anki could simply use a relative due date to decide which cards to review ahead. You would enter a percentage, let’s say 5%, and the custom study would be built with the cards which are due in the next `(card’s interval) x 0.05` days. For example, a card with an interval of 20 days which is due the day after tomorrow would not be included (because `20x0.05=1<2`), but a card with an interval of 80 days which is due in three days would be in the custom deck (because `80x0.05=4>3`).

What do you think? Wouldn’t this kind of custom study disrupt the calculated ideal intervals a lot less?

A common use case for “review ahead” is doing some extra work prior to taking time off, like covering a weekend’s reviews before you go away so they’re not waiting for you when you get back. Having the selection criteria based on % of interval elapsed instead of the number of days left might offer less deviation from the scheduled intervals, but it would mean you could end up reviewing cards that were due further in the future instead of the ones that occur during the time you’re away.

1 Like

Of course, with my suggestion the reduction of the workload earned by reviewing early would be spread over an undefined period of time. I didn’t consider the use case, you are describing.
So the relative ahead review shouldn’t replace the current custom study, but be another option for a different use case. Maybe I’ll try to write an add-on and see how it works out.