I think the problem arises that some of the guys you've observed doing this may have done USSSA ball. In slow-pitch in the past (and I know this because I do slow-pitch), it was required to give a VERBAL request for time. We were told to ignore the hand request, and the rules also indicated we didn't have to call time if the batter was out of the box and didn't request time verbally. I think what happened is some of the fast-pitch umpires in USSSA picked up on that, and decided to apply it. The rules have since changed that the batter has to be in the box for the pitcher to start any kind of pitching motion (except the windmilling fancy schmancy stuff in slowpitch) and if their hand is up, we honor that as a request, basically following along the lines of other codes. Maybe some ucking fidiot hasn't caught up to the correct rules on that?