I have been using the dull glow (cherry red) for quite a few years now, and I only look for it inside the neck, I find it is very repeatable once you know what to look for, you have to be very very vigilant as the case leaves the flame. This normally coincides with what I believe is called burn off and the flame changes colour. Years ago this was said to be to hot, but if you watch the Benchsource annealing video this is exactly what happens.
I did a test a few years ago with brass annealed at 3 different temperatures and tested I believe at 600 yards, the third set of cases I expect 99% of people would have said they were over annealed (if only I had made a video) I will have a search for it, although I was informed that my test groups of 5 shots for each temperature were not enough.