I have only annealed cases for two calibers I load, one is the 7x30 Waters for my Contender, and the other is my 25-06 AI. With either of these cases are easily acquired so playing with the Tempilaq and setting up a small jig of sorts was fairly easy to do, with not much expense involved.
I tried it a couple of times using a clock setting out behind the set up to monitor about how many seconds it took to turn colors. Once it did I, I jotted down the times form just starting to turn to completely turned. I did a batch of 10 for around 3-4 different times all within a 5-6 second spread. After this I headed up to the farm with them bagged up in separate baggies and gave them a go to see how they fared against non annealed cases.
As to the initial fireforming, all of the annealed cases formed perfectly with the first firing. The same couldn't be said with the once fired stuff I was using with it. All were loaded with identical charge weights and so forth, only differences were the annealing. With the untreated cases, I experienced both unformed shoulders as well as a coupe of split necks.
In continuing on, I found the treated cases would go about three to five loads longer before I started to see any sign of the sizer getting sticky, or a difference in seating pressure that I could notably feel while seating the bullets. As well the groups were all more consistent with the treated cases.
While it might not matter with plenty of calibers or even with most reloading and the groups gotten by such, there are a few cases in which it DOES make a substantial difference in performance if done properly, even with the most basic of tools. I do however agree, you have to set everything up so that you get as close to the same results from one case to the next. I used my cordless drill set to the lowest speed it would turn. I used a bracket I had from building fishing rods to support it in the exact same manner each time, and it held every case in, or extremely close to, the exact same position in the flame. I used the Tempilaq for the lowest recommended temp so I didn't get carried away with things. The water I used was a 5 gal bucket 3/4 full and never even warmed up in doing 50'ish cases of each in an hour or so period. This was only MY proceedure and it works for what I need. It may or may not work with my .270 or my .243, but I would wager if needed, I could easily adapt to what would.
IF you have something that may benefit from it, and do it properly, it is a very effective means to increase the longevity of your case life, especially if your not wanting to waste barrel life or components forming cases or mess with cleaning the cornmeal out of your action or a custom barrel.