If 600 people arrive on one plane then it will take 6 hours.
Common ! have you ever flown through Dubai , FRA , SIN or CDG where multiple 380s arrive at the same time ? First some arrive at different terminals, the disembarkation is done on 2 different levels and then the electronic booths or immigration agents are proportional to the number of pax expected. What is the difference between an 380 and 2 777s on opposite gates on the same prier ? all go though the same immigration booths at then end of the pier ....