ICN morning queues

Heading into Seoul for work next Saturday. Usually arrive at 5am and taxi to hotel so I can get some sleep before appointments at 11am. However, last 2 trips my experiences of getting through immigration have been very different to the last 2 years.

The normal 15 mins immigration queue has been around 90 mins the last 2 trips. There was only one member of staff on the physical counter, who was also letting people in the priority queue go ahead of the line they were serving. The queue barely moved till 7am when more staff came and then everything was handled in minutes.

So my question is, is this the new norm in an attempt to push people to register for the SES gates? Has anyone landed around 5am in last few weeks and can report their immigration experiences? If things are still the same, I'll cancel one nights hotel stay and just go get breakfast. Rather than spending so much for an hours nap.

Thank you for the replies, they'll be very helpful (and yes, I plan to register for the SES but my last few flights were all out of office hours)