From my experience lately at Austin's west checkpoint, it typically has a line with hundreds of people in it during the early morning hours. It queues all the way to the Southwest check-in and back past the AA and UA desks. If you don't show up two hours before your flight (or have elite privileges) you're probably going to miss your flight.

So with that in mind, imagine waiting to go through one of the 3 lines (two with NoS) and then rushing to your flight, only to miss it because the TSA is playing a "what-if" game.