Is the effectiveness of FSRS affected if you often encounter items of knowledge outside of Anki? I could ask the same question about SM-2, of course.
For example, if I’m studying a language, suppose that some word will be due tomorrow in Anki, but I’ve forgotten it, so when I review it, I will mark it Again. But in addition to using Anki, I’m also reading and watching videos in the target language, so let’s say I happen to encounter that particular word “in the real world” today, one day before it was due for an Anki review that it would have failed.
So I will remember the word temporarily, and when it comes up for review tomorrow, I will mark it Good instead of Again. Then FSRS will assume that I remembered it well and increase the interval, possibly to a very high amount, which is probably the wrong thing to do. Because I didn’t really retain it through the previous interval.
Language learning in particular is different, I think, than things like medical studies, where the chances are probably considerably lower that you will coincidentally encounter items of knowledge outside of Anki.
When you were researching FSRS, did this issue come up?