I missed this thread!
I do use a chelating after touchups, too. I have to.
I was noticing that was hair was kinda feeling odd on the days between my relaxer and next wash. I always using my chelating shampoo on wash days but I was not using it on relaxer day.
So I started using a chelator and I can tell a difference. I really like those Crystal Clarifying packs from Sally Beauty on relaxer day. They are sulfate free and I feel that my hair does not need anything stripping on relaxer day. if I don't have any of those (I think the cost can be too much for what you get), I will use my tried and true Kenra Chelating shampoo and it does the job.