Life span of a Carbon arrow in my experiance ends when:
1. a solid rock or other extremely hard surfaces are hit
2. your buddy or yourself " accidentally" hit your arrow while practicing
3. Animal you shot with it does not get a pass through falls and breaks the arrow, or breaks from running and catching something.
4. if your using lumenocks the prongs will over time being shot work its way and start cutting into the shaft.
and of course using too soft of spine in a high poundage bow is a no no and typically results in a 1 time use arrow and you may or may not hit intended target, with a good possibility of paying the emergency room a visit.
My choice of carbons, Carbon Express Maxima Hunters