Originally Posted by
rickair7777
If one were to exercise one's part 91 option to go down and take a look, and the official vis was reporting too low, it's conceivable that you might need to explain your flight vis. Or if RVR dropped after the marker for 121.
But if the official reported vis is good, then it should never be an issue.
I believe JohnBurke's response above summed things up correctly.