Solid 5 year interval

[Hairdude1]

Originally Posted by PJ S

5 years would be a bare minimum nowadays, what with the tolerance level of the parts and the synthetic lubes used.
Seals should be good too, but a pressure test every 2-3 years is worthwhile, if you plan on using in water beyond showering and washing dishes.
Many people subscribe to the service only when it shows signs of needing it – timekeeping being the main focus.

If you invest in a $200 or so Chinese made timegrapher, you’ll be able to monitor all your watches for amplitude, beat error, and accuracy, which will give you a clearer picture of when it starts to show a watch being due a service.