iwc AQUATIMER CHRONOGRAPH Mode D'emploi page 39

How often should my watch be serviced?
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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 April 2011.
Technical specifications subject to change.