Originally Posted by mritty

And once you allow +/- 5, then A25 boards after A20, skipping 21-24. Then the system allows A30 to board, because it's 5 greater than the last guy, still skipping 21-24 in addition to 26-29. And then A35 could sneak in, still skipping 21-24 and 26-29, and also 31-34. Because the system has absolutely no way of telling whether 21-24 are still sitting there waiting to board or if they're a family of 4 who took a different flight and didn't bother telling anyone at Southwest.