I never knew that was something you could do to begin with.

The utility also seems rather dubious - presumably you scheduled things like getting picked up from the airport and hotel stays based on the flights you were planning to take. If flights are frequent enough that your plane landing a few minutes early would allow you to catch an earlier flight, how much time are you really shaving off? Are you really going to throw your plans out the window for the chance at getting to your destination an hour earlier? I don't really travel that often, and when I do I like to minimize stress, so perhaps I'm just not the target audience here, but I don't think I'm going to be running across an airport to catch a flight I'm not supposed to be on.