A well-kept secret...
Escalator, left turn, conveyor belt, right turn, staircase, long corridor... Getting to Montparnasse station from the platform of line 4 at the Montparnasse-Bienvenüe stop is hell! When you're already in a hurry to catch your train, those long minutes spent twisting and turning in the corridors can be a major source of added stress.
However, the station's regulars know that it's much easier to get to the station, so they only share this secret with their closest friends, and laugh inwardly as they watch the tourists hurtle through the interminable corridors... We're joking, of course - Parisians aren't as haughty as we're led to believe!