Okay, so the judges see each act for about 3 or 4 minutes, then a minute or so between each one. so 5 minutes per act.
Working from 9 until 12 and then 1 until 5 means 7 hours a day.
So they can only see about 12 acts per hour, which means 72 a day, so are we supposed to believe that they see all those hundreds of people that turn up???
BTW I have read BEn Elton's Chart Throb, which is what made me think through this!