There are several factors:
1) pressure of the loads fired in the cases.
Cases stretch more with high pressure loads than they do with low pressure loads. Higher pressure aggravates some of the other factors.
2) Headspace.
The case is driven forward in the chamber by the firing pin, and then case then expands in the chamber and adheres before the case is driven back against the bolt face. That small distance results in the case stretching lengthwise.
3) Cases also stretch radially to adhere to the case, at least forward of the case web where the case adheres to the chamber.
4) How the case is sized.
If you use a small base to resize the case back to it's original dimensions the brass is worked a lot more than one that if full length resized, or one that is just neck sized.
5) The chamber makes a difference.
If it's cut with a new reamer it's dimensions will be on the loose side of the SAAMI or CIP tolerance. If the reamer is old and worn the chamber will be on the tight side of tolerance. Cases fired in that chamber cut with a brand new reamer will be stretched and worked more than in the chamber cut with the old reamer.
6) Some chambers are loose by design.
The .45 Colt for example is a black powder era cartridge. In that era the usual practice was to design the case with a slight taper in the body and give it a slight bottle neck. The bottle neck helped the case seal against the chamber quicker to minimize the gas coming back into the chamber and the action to reduce fouling, while the slight body taper ensured that as soon as the extractor moved the case aft the whole case came out of contact with the chamber wall. Those features along with a wide and thick rim helped ensure positive extraction from black powder fouled chambers. The .44-40, .38-40, .32-20 and .25-20 are all examples of smaller cartridges designed for lever action rifles that could do double duty in a revolver that employed all those features.
The .45 Colt was different. It was designed with no bottle neck and parallel case walls so that it could hold a maximum amount of powder. It also had a small diameter rim as the rim was only needed for head space purposes as the Colt 1873 SAA used an ejector rod, and a smaller rim meant a smaller cylinder diameter could be used.
Still, Colt hedged it's ejection bets and tapered the chamber by .007" from mouth to base. But that meant the .45 Colt case body had to stretch radially out to the chamber wall, around .0035" at mid body, on top of the regular clearance.
It isn't a big deal with black powder pressures around 17,000 psi, but when you start bumping them up to 21,000 psi tier 2 loads or 32,000 psi tier 3 loads, case life gets short. Maybe 5 reloads at 32,000 psi before you get spider cracks in the sides of the case.
7) case design also matters.
Cases with long tapered bodies are shorter lived than cases with sharper shoulders. The .22 Hornet is a good example. It was developed as a smokeless powder wildcat from the black powder era .22 WCF, using the above mentioned tapered body and mild bottle neck techniques to ensure reliable extraction.
However, case life with the .22 Hornet is poor, specially when loaded to higher pressure. One of the major advantages of blowing the case walls out and the shoulder to a sharper angle in the one of the several .22 K-Hornet chambers is that in addition to another 150 fps from greater powder capacity, you get much better case life as you can effectively headspace it on the shoulder and minimally size the case.
8) Belling and crimping
In straight wall cases, how much the case is belled and crimped has an enormous impact on how much the brass is worked at the case mouth and how long it will last until it cracks.
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So pistol wise at one end you have cases like the .45 Colt and .22 Hornet and on the other end you have cases that last basically forever like the .45 ACP and 9mm Luger.
Both the .45 ACP and 9mm Luger serve just fine until the case mouth cracks. The .45 ACP and 9mm Luger both headspace on the case mouth. If you use FMJ or other jacketed bullets that don't require the case mouth to be belled, the brass is worked very little.
The .45 ACP in particular when fired in a snug match chamber just goes and goes and goes. I'll reload them until the mouth finally cracks, then shoot that round anyway before pitching the case into the recycle bucket. I don't bother sorting and counting but the number of reloads per case is probably well north of 30 with jacketed bullet lower pressure target loads.
