User blog comment:IamJakuhoRaikoben/Chapter 335: The Time of Life, Review./@comment-1535822-20130614204951/@comment-3290324-20130614205830

Well, Hungry brought up a good point. She was reversing time for the entire world. Think about just how massive the world is. Ultear is a powerful Mage, but she's only one person with a limited amount of Magic Power. Having her set back time for too long would be very OP.