The games at this point in the tournament tend to run over 2 hours, even if no overtime periods are required. Often there are a lot a free throws due to fouls, and those take place without running the game clock. So, because CBS is carrying the rest of the games from this point onwards, the second game won't start until the first game has wrapped up, even though they're being played in different cities. That is how the delay could happen even without any overtime. What's remarkable this year is that there have been very few blow-outs and very few overtime games.