The presence of undervalued cognitive functions in writing, speech, and behavior does not mean the individual values these functions most. For instance, an Fe valuer, writing about subjective ethics, or using language that is indicative of an Fi dominant, does not mean that the individual is an Fi dominant. A Ti user, requesting factual evidence for a claim does not make that individual a Te valuer. Using a function other than your most preferred in an observable way, does not mean that you prefer that function most. Otherwise, the claim that each individual uses all eight functions is likely false.
In addition, valuing a function most does not mean that all individuals who value the same function most use it the same way or with the same strength. It does not follow that if person1 values functionX just as much as person2, yet is noticeably weaker, that person1 does not value functionX.