True to a degree, but the actual degredation of the world occured over a year, as stated (SPOILER)when Celes wakes up in the cottage Cid set up; he tells her that she'd been unconscious for about a year and that, over that time period, Kefka had been methodically destroying the world. So while in theory that is true, it is implied in most of the FF games that the world-shaking calamities occur in a time period spanning more than a few days, except for the (SPOILER)destruction of Midgar at the end of Final Fantasy 7, if you really can count that as a tragedy.