When you only neck size every reload and only FL size when you need to, your not work hardening the body of the brass like you do if you FL size everytime. So ya, case head separation is minimized or delayed. Most of the time you will see the primer pockets weaken before case head separation happens. So your on the right track! As long as the case neck still gives you good bullet tension and the primers still seat tight your good to go. If the neck tension becomes an issue and the primer pockets are good, anneal the brass and keep going. Because your loads are hot just keep an eye on the case head and you should have no problems.

Of course there are always exceptions to the rule and I'm sure someone here will point that out!

I believe it still happens but much slower. But I never load any of my rounds 11 times either. I usually get tight chambering with collet sized necks after 3 to 5 firings.

I generally am not able to reach anything after 5 or so loads. Either I start getting loose primers, or an ocassional cracked neck. I do anneal anymore and that helped the necks.

Does anyone find case trimming any sort of indicator, or just assuming thicker necks are the norm?

Brass will always push forward. No matter if neck sizing or FL sizing.

I have found the dreaded donut right at the shoulder/neck junction, and that was with neck sizing. So that tells me things are always moving.

Probably so on some chamberings. But something like a 22-250 tend to stretch pretty much the first firing and will continue to do so to a point. If they would need trimmed more than once, I pitch them.

Yep. My point exactly.

I guess I'd have to feel that was incumbent on the reloader to determine when the cases needed trimmed. (Using common sense and a good reloading manual). Personally, I'm the kind of guy who runs his cases thru the trimmer every reloading. Now I guess neck tension becomes a guessing game..?? Anyhow, on the short end of this, as I said before, I've learned to count to five, and I pitch....

Mine are tossed after at the 4th re-load. Cases used for hot loads are tossed earlier.