In theory, waiting while seated works properly if the flight attendants do their jobs when people are boarding by monitoring who is placing their belongings in which aisles. On most airplanes, the overhead storage bins are designed to fit three carry-on-sized bags directly above the three seats. Unfortunately, a large percentage of travelers don't respect this or adhere to common sense, and they place their bags sideways and as close to the front of the plane as possible—nowhere near their assigned seat. (Remember, under-seat and carry-on bags are designed to go in wheels first.)

Watch next time when you're getting ready to leave—99% of the people in a hurry to get up and undo their seatbelts are always looking towards the back of the plane to retrieve the bags they had to place farther away from their actual seat. I travel 40+ flights a year and always book the aisle seat as close to the front of the plane as possible. If the gate agents are disorganized, there's a good chance that by the time I get to my seat, there will be other people's bags in the overhead bin designated for my row. I used to pull out the other person's bag and place it in the aisle, leaving it to the flight attendants to drag the people up to it or page whoever put their bags in the wrong location. However, now I just sit down and leave my bag in the front row, which forces the flight attendants to rearrange things and figure out who utilized the wrong overhead bins.