Good question and totally subjective in some ways, but here goes.
If it isn’t important, I leave it on the closest WB setting to the conditions and leave it there or sometimes Auto WB if it’s doing a good job. If I feel the WB will be critical or if Auto isn’t working, I start in the field by looking at the scene and comparing it to what I see in the viewfinder and the back screen. Since they are both OLED screens (mirrorless) the result is sometimes different between the two and I choose which is closest to what the scene looks like. I start with one of the standard WB settings in the camera and adjust as necessary. I can get pretty precise with it in-camera.
This is helpful for times when I probably won’t recall accurately the particular shade or nuance of a color. Read most of the time. So it becomes important to me to get it as close to reality as possible to begin with; that way I don’t second guess myself. If it still doesn’t look right in editing software I’ll finesse it a little.
Rarely do I take a lot of license with color shots. Only if a big change suits the photo in a way that is better than reality. Sometimes I’ll go further if I want to create a moonlight effect or something similar, but it’s rare and I usually explain what I’ve done and why.
Black and white is different - often a change to the white balance changes the gray values of all the colors in the photo. That can really alter the mood, depth, tonal range and even the internal composition of the shot. I start there and then mess with everything else.
Boundaries are my own sensibilities with my intent and the natural environment I’m showing in the picture. If they don’t match, look fake, weird or just plain awful I don’t make big changes.