At one point last year, I had seven itineraries in a row with at least one late segment. I have quit counting because getting out of LAS in the evening, I have come to expect delays. Quite often, going standby becuase my flight is is late means getting on a flight that is less late.

What I have found there and at other airports is that later in the day the delays pile up, even when the FAA map shows nothing but green dots across the country. I can only figure that this is the offshoot of the system of flying a plane point to point to point. If you fall behind early in the day, it is hard to make it up. With a hub, there is at least some chance of swapping out equipment. I know WN does some of that in LAS, but there aren't enough cities where it has a large enough concentration of flights to do that.