Unless you are willing/prepared to do it right, I would not play with annealing cases. If you are
willing, then measure the depth of that willingness by getting the necessary temp/indicator wax/liquid that permits you to determine case critical body temperature whereupon you quit heating the neck shoulder.
I use "tempilaq", which appears a lot like white typing correction fluid and goes on with a small self-contained brush from the bottle (just like correction fluid).
It goes about 1/4" below the neck and dries white.
As it spins (using a hand drill) in the flame (deliberately directed at an angle to concentrate on the shoulder/neck), the white splash mark goes transparent when the case body at that point reaches (in my case) 475F.
At that point the neck is "done" and the case is dumped.
As you can see, the cases are precisely annealed neck/shoulder, with the end
of annealing about 1/8" below the shoulder. It can go lower (to a 1/4") but there it's gotta stop
Unless you are out after <1/2 MOA, and/or getting split necks, and/or the neck expander "screeches" (brittle brass) as you pull the case from the sizing die, I wouln't mess with it.