Imo weight class should be determined by an average of a bunch of weigh-ins for weeks or months before an event. Then, on the day of the event, allow some tolerance over the max weight but only if the average stays under. If the average creeps up into the tolerance zone, then they go up a weight class. Make the weight classes based on healthy habits rather than basically cheating in an unhealthy way to make weight a day before, then bulking back up to whatever weight for the actual fight.
Not that I have any stake in any of that, so my say isn't really relevant.