That's not quite correct. It depends in what rifle you shoot them in. Remember brass will stretch when fired. But then again, it's your brass so you can do whatever you want.
Oh no, it is absolutely 100% correct. For me, in my world.
I trim *my* 223 brass back to 1.740. This is approx .010 below trim length in most manuals. It is exactly what I do.
It will take more than a few firings to get grow .020 and get close to trim length again. By that time I just assume it is getting a little thin in the web area. Rather than separate a head and leave the rest in the chamber, I just toss them.
In a bolt gun I might get a few more reloads than out of a gas gun, but I take a lot more time reloading my bolt gun ammo.
Sometimes I even trim my 223 brass back to 1.355 and put a cute little 30 caliber shoulder on there and call it 300 Whisper.