Due Today
Plus Every question you answer anywhere in Recallab joins a review queue. Due Today is that queue, on the day it comes round.
What it is scheduled on
Two things: whether you got it right, and how sure you said you were. A question you knew cold waits a long time before returning. One you got wrong comes back soon. One you guessed correctly comes back sooner than the interval a correct answer would normally earn, because the schedule does not treat luck as knowledge.
What it is not
It is deliberately not FSRS or plain SM-2 applied to flashcards. Those schedule a card you grade yourself after the fact. Recallab schedules the question, from evidence it already holds — the answer you actually gave and the confidence you actually declared, recorded at the moment you answered rather than recalled afterwards.
Using it
Open it and answer what is there. If nothing is due, nothing is due — the queue does not invent work to fill a day. Answer questions in any other mode and they join it for later.
It is the one thing in the app worth doing daily. Ten minutes on what is due beats an hour on fresh questions you will have forgotten by the weekend.