Data maturity and reliability are at their lowest when assumptions (fill-in information) and constraints peak. The rule of thumb to follow: Projects should not be sanctioned when the unknowns far exceed the knowns.
Data maturity is a project attribute project managers have to deal with in some intelligent way. They seek to formulate a way to address missing and incomplete information and strike a balance. Integrating a project with missing or insufficient work scopes is not ideal. Filling in an information space with assumed fill-in data is a risky trade-off.