In my recollection of Star Trek TNG other officers frequently ask Picard for permission to speak freely, which he seems to always grant.
Is there ever a case where Picard denies an officer permission to speak freely?
The closest I can find to Picard censoring an officer (Riker) is this clip:
This was during the episode Sarek.
He also, somewhat famously, told Wesley Crusher to "shut up, Wesley!" during the episode Datalore:
However, at the time Wesley Crusher was not an acting officer (he became an Ensign later on in the series).
Ensign Ro was denied permission to speak in the first episode where she was introduced, although I don't believe she formally requested such permission
PICARD: You do not leave this ship without authorization.
RO: Captain, I'm sorry, but...
PICARD: This is not a discussion. You're restricted to your quarters for the remainder of the mission.
Searching the scripts I found that, indeed, Picard has never denied anyone permission to speak.
Quite the opposite:
RIKER: Permission to speak candidly, sir?