a few years back I had the option to fly pit-las on a single flight # (same-plane, with a 25min stop in MDW), or a two-flight # trip BUF-MDW-LAS.
I chose to fly BUF-MDW-LAS so that I grab potbelly for dinner
As luck would have it, the PIT flight was delayed and the 25 poor folks who booked a 'direct' flight missed the MDW-LAS continuation portion of their flight.
Rare, but it happens. flight crews were timing out all over the place.