Normally, yes. But this morning at about 05:30 I arrived at ICN and saw huge transit queues, the longest I've ever seen. Immigration queues were normal for that time of day. Not sure why the transit queue was so long. There must have been close to 100 people in the queue, though I couldn't see exactly the entire queue from my vantage point, so it could have been even longer. Note that in my experience delays with transit or immigration would normally only happen in the very early morning when a large number of inbound flights are scheduled around the same time. For those arriving later in the day, I don't think there's any other time when such a large number of nearly simultaneous arrivals are possible.