This doesn't happen all the time, but there have been a few times when I've been farming the Sunken Citadel that leaving to the Ashen Waste (on the north side) and re-entering the Citadel will instantly reset the Minotaurs and chests and traps; no rest needed, virtually no time passing. I tried to re-create the situation but I couldn't, and then last night it happened again, same situation; I leave through the north, immediately go back down to the Citadel, and the whole place reset.