Friday => penitence

Someone wrote here in a comment recently:

We're now riddled with self-credentialed liturgists and DREs who quote each other as if they were magisterial, and who are genuinely clueless when you point out the facts, quoting chapter and verse from CVII dos or the GIRM.

I can’t speak to the overall veracity of this description, but I will share that my parish’s new DRE did not know until I told her recently that Friday is (still) a day of penitence, on which we are still obliged to make some act of penitence.

(A pretty good proof-positive, btw, of the penitential character of Friday is that Lauds begins with Psalm 51 on every Friday of the 4-week psalter.)