I have mine high-low lighted about 3-4 times a year by my stylist. I go 2 levels light and only one dark, because my hair grabs the black in the dark. I am also a non practicing stylist. I used to tell my clients that I was Licensed to ruin their hair whan they came in with problems.
Everyones hair takes color differently. I am naturally about a level 4 which is a dark medium brown. I do not let people use bleach to hi-lite my hair as I would look like the cheapest girl on the street when it was done. (yes, someone did it that way.) I had a "blonde" woman come in with what I called bottom of the lake muck green hair, as she wanted to lose the "brassy", but her hair took the ash. I had to correct another womans hair after she wanted the "burgundy" look that was popular a few years back, and it took the red violet shade and not in a pretty way. When people tell you to go ash, remember it will have blue and green in it, and you hair may take one shade over the other.
And actually if you follow your color wheel theory. you have to correct the hair color with the opposite color on the wheel. To control brassy(orange)- you need to add green, but not go overboard. What works for one will not work for the next, that's why so many of us will pay the haevy price to have some one put the color in.