The determination of "weight" is, in a sense, subjective. There are very predictable positions in the watch's posture. One of them is "Dial up". We assume that 8 hours rest and the clock as norm is in that position. That position will have more weight. There are less likely positions: Dial Down. Although not common, if possible. For example when our palm is up. That position has a smaller "weight." The "crown up" position is unlikely too, and it is presented when we raise the hand to the height of the face and the elbow in its lowest position. And so on. Although we can make an average we give priority to certain positions. The watchmaker should know to some degree the habits of his client. Or if we do it without being watchmakers, we know our habits. This is my opinion, and I would appreciate if anyone can add something to this.