Anki 1.0 had a similar feature but we do things a bit differently now. The
relative spacing applies only to reviews, and spaces cards according to their
interval, instead of spacing all cards the same. Any delay < 1 full day is
treated as no delay, so with the default 10% setting, reviews with an interval
< 10 days are not spaced at all. This should hopefully cut down on support
queries for people wondering why many of their cards were delayed, allows the
two settings to be documented separately, and does away with the somewhat
confusing usage of non-integer new sibling values to disable review spacing.
- this fixes a state where cards failed on that future day could end up
with an earlier due date that the rest of the failed mature cards, leading
to the newly failed cards being repeated prematurely
- this leads to non-deterministic scheduling of the mature bonus fails, so
they are effectively randomized which is probably what most users want
This works fine if the user is showing all cards, but if they have limited
reviews to certain categories, it can result in the counts going negative
because we decremented for cards which weren't actually due. Determining if a
card was actually due or not is an expensive operation, so instead we leave
the counts alone and make sure reviews will finish early if the new/rev counts
are non-zero but the queue is empty.
because field formatting is always on now, users with custom font
sizes/families set only on the card will still have to alter their templates
and either configure the fields or replace the references with triple
curly braces
