I'm just starting to more fully understand custom white balance and have been fighting WB issues since I bought my first point & shoot in 2002 or so. Coming from 35mm, it never dawned on me the odd color renditions were light source related. And that, coming from one with an array of light-source correcting filters for 35mm film! Duh!
So now, I recently switched to RAW+JPG and have learned to set custom WB in the camera using a grey card or my ExpoDisk, whichever is more convenient.
As most of my shooting is done indoors under a wide variety of lighting, some with mixed lights, some with sunlight into an incandescent-lit room, etc, I'm learning by experience to set custom WB for each exposure situation. One small party I shot I had a wall of sun-lit windows on one side, and incandescent lighting on the other. Each of my shooting directions (relative to the windows) was a different WB setting.
I'm also learning to use the WB dropper in Lightroom. As a result, I can now go back and re-do the screwed up WB I had on my (ex-) step-daughters wedding 2 months ago.
For outdoor shots, AWB works fine. Indoors, I'm going to CWB -everything-! I'll be setting it in-camera for the JPGs, and using the dropper for those I edit from RAW. I've been burned too many times in the past to not CWB indoors! Lesson learned the very hard way!