I always screw up my first character's appearance in TES games, and then fix it later with ShowRaceMenu and mods. So I don't have to restart. My later characters don't need fixing.
From time to time I think my character needs tweaking, but then when I test changes I find out that any changes weren't required after all...the character just became worse. I think that with ShowRaceMenu many would soon realize that changes to their character weren't necessary after all. Unfortunately console players don't have the command so they could test tweaks later in the game.
This has always been my main problem with male characters. I am very not-happy with my Skyrim males and would love to edit them afterwards but unlike Fallout in Skyrim using "ShowRaceMenu" console command messes up your skills, so it's not really an option.
Only once ever I've been content with a custom-made male character, and that's the Fallout character appearing in my avatar.
Females I am much less critical with. As long as they look hot, I'm cool with them. Cosmetic mods help a lot with this.
I've found out that if you switch between genders once in the ShowRaceMenu screen before editing your appearance your skills don't become messed and you don't lose racial abilities. Changing races messes up skills, and if you don't switch between genders once you lose racial abilities.