Falcon 9's first stage can be reused 10 times or even 100 times.
But how about its payload fairings?
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There is no inherent limit. As long as a fairing can be retrieved, and repaired if necessary from seawater corrosion or landing impact, it can be reflown. A fairing has no parts that wear out due to use per se, like a car tire's tread or an Apollo Command Module's heat shield.
Its steerable parachutes need to be cleaned and repacked after a flight, but they can last a long time:
A properly stored reserve, with few repacks/rides, should be perfectly airworthy 20 years later.
In the United States, the FAA has not imposed any general time-based lifespan on gear. ...
In Poland, it's unlawful to jump any skydiving equipment older than 20 years.
It's typical to inspect and recertify a conventional skydiver's reserve chute after 40 repacks or 25 deployments.
So the chutes might last easily a few dozen half-hour flights before needing serious inspection, never mind maintenance.
Its cold gas thrusters need to be refueled after a flight, of course. (See also Do each of the fairing halves now use thrusters post-deployment? How does that work? ) But they seem to be intended for continual reuse, as of 2020 June 16:
Although there has yet to be any official confirmation that Falcon 9 fairings are capable of flying more than twice, there's good reason to believe that the design upgrade that enabled one reuse had some built-in headroom. ...
It took SpaceX some 33 months to go from the first reuse of a Falcon 9 first stage to the second reuse (third flight) of a single booster."