I was on 2 Delta flights recently where the
secondary screening was done right as the passengers were attempting to board the plane. Not only did it keep exactly who was about to be screened confidential until the point of boarding, but it also prevented the situation where somebody who is called for secondary screening ignores it and boards anyway, then causes the entire plane to be emptied and re-boarded. I think somebody finally realized how idiotic it was to announce in advance who was going to be screened. All the terrorists would have to do is travel in teams (each person with a separate reservation), then hand the prohibited articles off to one of their colleagues if their seat number was called
(or if traveling alone, just dump the contraband into a trash can and try, try again on another flight).