Connecting through NRT, even at peak time, I don't remember security ever taking more than 10 minutes, with almost the same numbers of passengers, staff, and only 4 lanes open. ICN has had the slowest security lines (in recent memory), counting both transit and departure security.
I transited NRT in December and it sucked. I used the premium line and it took 20+ minutes to clear. The regular line looked considerably worse. The staff who review docs and feed the bags into the x-ray machine were working very, very slowly.