If I decide to try a different brand or weight of carry ammo I shoot 100 rounds of it through any pistol I will carry with it before I consider it reliable. Maybe as few as 50 rounds in a particularly reliable handgun that has gone thousands of rounds without a failure with any type of ammo. After that, once or maybe twice a year I shoot the loaded magazines to refresh the carry ammo and test the magazine it is in. The rest is target ammo.

I do try to avoid weak ammo like Winchester white box though since I carry +P 9mm. It feels a little different. NATO spec and Speer Lawman is loaded a bit stronger, feels more like the ammo I carry and doesn't cost more so I typically use it for target ammo. But if I see a great deal on some other brand I will sometimes buy it, not that I have seen a lot of great deals in the past few years.