Here's what seems to be the case. Case life can be greatly influenced by AI or X-Die use...but equally influenced by case fit (tight chamber with minimal tolerances using the same brass like the benchrest folks), neck sizing only, how hot you load, brass brand and thickness, and case design. All of these things can be cumulative if you do more than one of them. So my answer is to use X-Dies when they are available, and AI and neck-sizing when they are not. Case closed. By the way, I consider X-Dies are a viable work saver even when you do not shoot high volume, a better mouse trap so-to-speak.