In some watches, this behavior is fascinating to observe. The momentum developed by this rapid rotation prevents added impulses from being applied during most of this process. Here, the main, and only, source of torque is the Earth's gravity, which keeps the rotor at the bottom of its arc of swing while the watch revolves about it. Accordingly, the rotor exerts a steady torque on the mainspring through the winding system's gear train and the mainspring is wound until it reaches the slippage point designed into its barrel. Then it continues to turn, this time with the outer end of the mainspring slipping against the inner wall of the barrel.
Excess energy is dissipated in the only way available, i.e., heat developed by the slippage.
And even beyond this effect, the inevitable consequence is added torque on the watch's main gear train and escapement. In such a case, the slippage may not begin to take place when expected and the winder can keep increasing the tension in the mainspring to the point that overbanking begins. The result is a drastic increase in rate of minutes per hour, lasting until the mainspring has a chance to relax to a normal level again and exposing the escapement parts to the risk of permanent damage. Interestingly, the above excess torque is far less likely to develop on the wrist, even if the watch's lubrication is less than perfect, simply because the impulses on the mainspring are short and sporadic as described earlier. The effect on the watch's rate in such case will be very minor.