Which is the same for any "professional" fitting; also realizing that they are using just another formula created by yet another person's beliefs on fit.

Fit Kit, Retul, or whatever are just systems based on created formulas. Once the bike is adjusted to whatever formula, having a fitter on hand can help to make tweaks as you describe the issues, because any formula doesn't account for a tight tendon, or former back surgery, a bakers cyst, or just general preferences, etc.