The convential wisdom has always been new cables each year. Back in the day I used to do that.
Now I don't bother. One bike has 6 years on the original cables, and the other has 3 years. No breakage,and no shifting problems. YMMV.
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.