Hi again TG!
I know Angie and YLF members' opinions on personal color analysis and flattering print/patterns varies greatly. Some very lively discussions over the years here and I'm always up for another!
Great question re systems that create truly custom palettes.
They're out there -- many derive from Suzanne Caygill techniques, including Carla Mathis' [The Triumph of Individual Style author mentioned above]. Some just start with System XYZ and encourage the color analysts to pick a "homebase season" and then whatever colors from other seasons work with an individual's coloring.
Sounds a lot like what some YLFers like Style Fan have experienced.
I'll link to Beauty Valued, a custom color consultant whose work I peek at now and again. She shows a palette she developed for a client who then brought in palettes that spanned the decades -- you'll immediately see the color harmony. And if you don't she walks you through it.
I'm one who believes 100% that we each have colors, color combinations, and print/patterns that make us look anywhere from stunning to godawful.
And I always encourage people to stay in end of the "stunning to good" end of the spectrum unless an item in question is a fairly small accent. Some have a much smaller range than others, it's true.
Perhaps ironically, my color palette is DIY.
But it works well enough that I now have a little word-of-mouth sideline helping others do the above in a very real-time way. I used to feel apologetic about not having invested in the drapes, swatches, training etc but people know what they get with me. They get someone in their closet, at the shops, and/or at the fabric stores sharing what I see in a very hands-on process.