I just obtained a watch that does not hack. It runs a bit fast so by the end of two weeks or so I need to set the time back. Talking in general, how many minutes could one safely set the time backwards on a non hacking movement without affecting the timekeeping? In particular, assume the movement doesn't stop when you do set it back, which is true in my case. Given the opposing forces, it would be helpful to also understand how movement designers manage this scenario, if at all. Thanks.