My 454 brass lasts for 8-11 loads. The part that wears out most often is the primer pocket expands to the point where i can push the primer in with my thumb.
I've been thinking of getting an anvil for this, but by the 9th or so reload I start getting split mouths anyway on some of them. I trim them between each loading, because they grow a little and I want consistency.
My loads are generally very light to medium. My heaviest in general is a 255@1500 and 325@1400, although I occasionally load to higher velocities for experimentation. 325@1550, 255@1880 and 225@2000 are about the stoutest experiments I've pushed.
I think much of it depends on the gun itself. A good inspection between loads is recommended.