Originally Posted by Kacee

UA used to have a systemwide practice of opening all fare buckets, including I and X, prior to departure. If there were empty seats, they would be offered for saver awards. Last year, they ceased this practice. Now they offer last minute saver awards for only a relatively small percentage of flights. And it's unpredictable so you don't know in advance whether the flight you're looking at will be one of the few.