Most (low cost) airlines I flew used one, or two at most, of the door. It would work even better if you could use doors on both sides of the plane. The problem

Most (low cost) airlines I flew used one, or two at most, of the door. It would work even better if you could use doors on both sides of the plane. The problem is that usually, in most airports, this requires more than a single jet bridge per plane or walking on the tarmac