I'd say 5 to 7 years if you want reliable rigging, esp if you race or head out on the ocean. you can get away with longer if your rig NEVER sees significant loading, or if it is stored well away from salt water.
the most common rigging failure I've seen is a shroud failure just inside the swage at deck level, where salt accumulates & the wire is strained. rig looks shiny 100%, but it is only as strong as its weakest link, which can be hidden.
poods