As a little experiment I decided to section one of my cases. It is a Lapua case in 308W and has been loaded about 15 times, approx 9 of those loadings have been with a book max load that is giving me in the region of 3000fps out of my rifle. Now the picture isn't great, and my cutting wasn't great either but I think it can be seen that there are no areas where the brass seems especially thin nor does it look like i'm heading for a head separation in the immediate future. The bit that appears slightly thinner, above the web on the right hand side, is actually as the result of a bit of an error with the dremmel cutting tool and if you look you can see that the wall appears to thin from the outside, where I touched it with the dremmel, rather than the inside.
I realise that none of this is rocket science but it was an interesting experiment and provides some reassurance that I'm not on the immediate road to ruin with my loads and cases.