Another simple thing that could be done to increase efficiency is have notices upstream in the security line instructing people to remove their shoes / belts a

Another simple thing that could be done to increase efficiency is have notices upstream in the security line instructing people to remove their shoes / belts and store their personal items like phones before they get to the conveyor belt used to feed items into the x-ray baggage scanner (assuming this is still a relevant bottleneck). A lot of time is needlessly wasted by people who start this process when they first hit the front of the security line.