To add to this, usually when I see a mess of a data model it's not because it started that way but rather it's indicative of changing business requirements with

To add to this, usually when I see a mess of a data model it's not because it started that way but rather it's indicative of changing business requirements with not enough time given to engineers (or more rarely lack of experience, I guess) to refactor / redesign / migrate things properly. Or perhaps original creators leaving with no record of why things are built a certain way so no one wants to touch it.