Archers aren't the best example – it's precisely ranged units in Castle Clash that allow you to break through without significant losses, because distance isn't a factor there, and unit speed matters (the same centaurs easily defeat slow-moving archers with minimal problems, which is impossible in melee combat). The example with iffrits directly confirms NumOne's words: a close fight, a couple of extra morale points, and the iffrit is gone, while a replayable quick battle allows you to "reroll the dice" and change the morale outcome. I don't use the 3+ mod, so I wasn't aware of the Q button, but if it exists, what prevents you from using it, engaging in a close fight, and pressing it if you're confident in the outcome? So far, the replayable quick battle is a safety net, and no other arguments have been presented (speeding up battles with instant completion should save at least as much time as a replayable quick battle). But the saving of nerves, concentration, and troops when using a replayable quick battle is an advantage.