I had a colleague who timed the loading of an all economy 747 - 8 minutes,
As for waiting until everyone else has boarded, some 40 years ago I met someone who had recently been to Saudi Arabia. He checked in for a domestic, went to the gate, watched the scrum when the flight was called and when he actually boarded no seat. Same again next day. Day 3 he had wised up, joined the scrum and got a seat.