We went through T1 domestic a couple of days ago mid-morning. Nexus line was closed at the time (clearly posted sign) and when I asked the person directing traffic if there was a premium or Business line they just laughed. Fortunately the whole process was quick - under 20 minutes, but heard a few complaints from people having to take out liquids, etc. unexpectedly "I have Nexus, Super Elite, yada-yada." Virtually every screening station was staffed, which expedited things somewhat, however the screeners were "meticulous", with almost everyone getting a secondary of some sort - wanding, bag swab or turn on electronics. If it had been busier I can see how things could slow down.