The myth of over-winding...
"Watches are often found stopped with the mainspring fully wound, which led to a myth that winding a watch all the way up damages it. What actually happens is that as time passes and the watch movement collects dirt and the oil dries up, friction increases, so that the mainspring doesn't have the force to turn the watch until the end of its running period. If the owner continues to wind and use the watch, eventually the friction force reaches the 'flat' part of the torque curve, and quickly a point is reached where the mainspring doesn't have the force to run the watch even at full wind, so the watch stops with the mainspring fully wound. The watch needs service, but the problem is caused by a dirty movement or other defect, not 'overwinding'."