iwc AQUATIMER AUTOMATIC 2000 Operating Instructions Manual page 18

How often should my watch be serviced?
The optimal service cycle for your IWC timepiece is
exclusive to your watch and unique lifestyle. The
necessary interval between services will be determined by
your individual wearing habits; frequency of wear, your
environment/s, and the intensity of physical activity you
engage in. Your fine mechanical timepiece is an extension
of yourself and will run well for as long and smoothly as it
is treated. Therefore, we simply recommend you to
continue wearing your watch for as long as pleases you
and to only entrust it for a service if you notice a deviation
from the regular performance, function or timekeeping. It
will then be our pleasure to reinstate the premium
performance with the suitable service.
Effective from January 2009.
Technical specifications subject to change.