I have no idea what an adequate answer might be to the original question. I do believe that that there is no general answer beyond it depends.
FREX for .45 ACP with a #130 cast and 3.5 grains of Bullseye my answer would be many times until lost or the lot shows too many split necks. With annealing that moment might be a long time coming.
Agreed that even one firing with signs of case separation is the end of that case. I do use the Redding Instant Indicator and Wilson gages and the RCBS case master and even a Hawkeye bore scope to check inside. The one barrel I had that did have head space issues the cases were saved as curios and sectioned for conversation pieces while the barrel was being replaced under warranty.
On the other hand I do believe that regardless of any and all other factors no matter how good the case still looks there will come a time when enough brass has been lost to trimming - assuming the case is trimmed which straight wall pistol cases mostly are not - that I will give up on the case or at least shift to powder puff reduced loads.
