I was mostly talking about specifically bred hybrid hens, that are bred to optimise egg production. But I am sure with any kind of bird there will be many exceptions where some lucky ones have lived nice long lives!
I sincerely apologise if I am mistaken. My vet did say that for hybrid hens...
Hybrids generally live for much less time than pure breeds, and hens which lay lots of eggs generally also have shorter lifespans due to increased risk of developing reproductive infections such as egg peritonitis.
Out of the hens I have had (all hybrid egg laying breeds) the oldest any have...