I often use my phone in the early morning while I stretch and do yoga prior to exercising. I feel as though I'm always tapping extra dim and the comfort shield to reduce the light from the screen. I honestly don't think I've ever used either by itself. If there was a way to link them in the shade, saving the settings last used or a customizable feature that would be great. In the UI, if they're linked, keep them dude by side, add a small link icon between them and you have a cool UI and a better UX overall.
This ^^^ I usually use both in sync. I currently have a routine set that enables both at certain times but having a toggle for both would be handy to use on the fly.