just my experience. I only fly Southwest, and as far as I can tell, people trying to board significantly out of order get scolded by the gate attendant and sent

just my experience. I only fly Southwest, and as far as I can tell, people trying to board significantly out of order get scolded by the gate attendant and sent back to their place in line. swa is first-come first-served seating though, and they charge extra for low boarding pass numbers, so it might be a bigger deal to them.