I wonder how much plane size impacts the efficiency of system, particularly in the case of the random boarding process? I flew on Southwest and American Eagle l

I wonder how much plane size impacts the efficiency of system, particularly in the case of the random boarding process? I flew on Southwest and American Eagle last week and thought about this for a while. On Southwest people were able to choose their seat based on their position in line, but that choice was harder for some people than others. On American Eagle (pre-assigned seats) the plane was so small (16 rows of 3) that they didn't bother with boarding order outside of priority status. People randomly tried to get to their seat on the plane, but it seemed like that was faster on a per-person basis than Southwest. Perhaps choice slows the system down?