Well, pairings that fall below the window of 6 to 9 hours are short enough you don't need a sleeper train: sitting in a train for 3 to 5 hours is not that bad.

Well, pairings that fall below the window of 6 to 9 hours are short enough you don't need a sleeper train: sitting in a train for 3 to 5 hours is not that bad. Pairings that are above the window are turned into a 6 to 9 hour sleeper train ride plus a regular 3 to 5 hour ride that's not that bad.