Sparky14 is right on in that it totally depends on how well they are removed and his assessment on the weight of the shaft (specifically the wall thickness at the tip). Too much heat can compromise the composite and resin in the graphite, but done carefully and correctly, you should be able to reuse.
Steel shafts can be pulled and reused no more than 652 times.
Graphite – it all depends on how well it was prepared and pulled. I used a set of graphite shafts in 4 different sets of iron heads. But those were an older 105 gram set of shafts with thick walls. Light iron and wood shafts have thinner walls. I am hesitant to reuse a thin wall graphite shaft after it has been through two heads, but I might still give it a shot at #3 if the tip still looks sound.