Curly45,
The life expectancy depends heavily on the cartridge, the pressure level of the load, how tight the chamber you are shooting it in is, how hard the brass is, and also on the resizing tools and method you to use, so there is no simple answer. I've gotten over 50 reloadings out of 45 Auto brass firing target loads. Some rifle brass can last that long if you anneal the necks periodically and are running them in tight chambers at load levels that are not excessive. On the other end of the scale, M14 match shooters used to reload hard military brass no more than four times, as the rough handling in those guns and hardness tended to put them at risk of head separation in the middle of a rapid fire string, not to mention throwing a case head with sharp edges at the fellow shooting next to you. Norma says they inspect their high power rifle brass to be sure to withstand at least 10 reloadings, but over-hot loads of belted magnum brass can have some of it stop on the third reloading.
So the answer to your question about brass life is, "it depends".