Generally, a watch that is regularly used often lasts 10 years or more between servicing.
Some sales people try to suggest that 5 year intervals are de rigueur but that's simply not true. They try to suggest that if you wait too long that more expensive parts are required to be replaced, which is generally not true.
Watches have lubricants, these lubricants do gel up after time and lose their viscosity over time. I highly recommend watches that have lubricants over 5 years be kept on a winder or wound regularly, to prevent the older lubricant from stagnating and gel-ing up. Constant use will prevent the lubricant from solidifying.
Lastly, since you presumably live in the United States, depending on which kind of Lange you have, I would simply wait until you have the time to visit New York City. Alkis, the officially licensed Lange Servicer in North America is based in Manhattan and he is an excellent resource for Lange watch owners. Go directly to Alkis in New York (bypass GO, collect $200, skip your Authorized Dealer) after you notice something wrong with the watch or if it's after 10 years and you happen to be in NYC with the watch. Give Alkis 2-3 months to service the watch and test it; and he will mail it back to you. Or, if you can, visit NYC again to pick up the watch! Allkis doesn't service every type of Lange, certain unusual/special models Lange requests Alkis to send back to Germany for servicing as they require certain servicing requirements, also Lange corporate wants to record certain data and evaluate the performance of these watches first-hand.