We run a spread offense with west coast principles.
You will need 6 quarterbacks (or as few or many as you want) all of which have a ball. You set up the quarterbacks every ten yards alternating them from the hash to the sideline. Receivers start in the middle of the quarterbacks in a single file line.
Receiver then sprints in a straight line between the QB's. Each QB throws their ball to the receiver. The receiver catches the ball and tucks it away and then drops on the ground before the next QB in the drill throws their ball. After the receiver drops the ball on the ground the QB goes and picks up the ball and returns to their spot in the drill.
Make sure that the receiver sprints, simulating game speed. Quarterbacks should always be on the sideline and the hash in order to keep the drill spread out. You may want to start quarterbacks 15 yards apart at first to make the drill slower. Make sure that receivers run in a straight line. They will have a tendency to veer toward the QB.
Receivers are forced to catch a large volume of balls at full speed in a short period of time. Quarterbacks are forced to throw to a receiver running full speed.