The first thing to go on most brass is the primer pockets, particulalry on Magnums. They become loose. Then, splitting of the necks, or case separation at the belt.
I have 6BR brass that has been used countless times. I have saved every bullet box I have ever used and saved them in a giant box. I got the brilliant idea to count 6mm 105 boxes, and I quit counting at 120, so more than 12000 bullets through my 6BR brass. I have had to discard only two from slpit necks. The primers are all tight, and I anneal after every firing.
My 6BR brass has outlived multiple barrels... If lapua don't make it, I basically don't shoot it.