If you're flying an E190, there's a good chance that they'll solicit volunteers for a free gate check (to carousel) at the gate. Each bin spans about two rows (so there's one bin for 4 seats) and really only holds about 2 and a half bags. So, there's really only room for about 50 bags on a plane that seats 100 (There's ~24 bins on the aircraft, and I subtracted 4 for the safety equipment, snack basket stash, etc).