Just take yesterday as an example: Around the time of the MAN flight were the following non-Schengen flights:
12:50 DY JFK
13:15 QR DOH
13:30 SK LHR
13:30 DY SPU
13:35 SK MAN
13:35 PC SAW
13:55 DY FLL
If the JFK flight would be half an hour late and FLL half an hour early, the MAN passengers could end up in an immigration line of 1,600-1,700 passengers.