"Knotline" the spring 2002 issue of a newsletter/publication from Hunter marine contains an add by Navtec rigging solutions. They don''t give a web address the advertisement is basically a how-to of how to inspect rigging and how often to replace it. The previous response was right on the nose. If in doubt on cruisers it says replace every 10 years. The item that should always be replaced in 10 years (or 40,000 miles) is the turnbuckle screws. Other items you can clean up and inspect for transverse failure points, but turnbuckle screws can hide the apparent weak points until you lose a mast or result in heavy repairs.
I am as the nomenclature indicates a severe rookie, just passing on information contained in an advertisement. Let me know if you have any questions and I can reference the article (but not my experience, ha!)