I have my brightness and volume both set to 75%. The Ultra is bright enough that I can probably bring down the brightness to 50%, but I don’t know if that would even make a significant difference in battery life.
This except also 50% with sound on my Series 8. I’ve never felt the need to adjust brightness and sound is usually mutedI've never adjusted them AFAIK nor felt the need to, but I just checked and my brightness is at 50% and my alert volume sliders is a little over 50%. Series 6.