The only time (to my recollection) that our DS in Cornwallis used the term "etiquette" (which was unlikely) or "good manners" was after one of them happened upon a recruit (who did stay long on course) alone in the communal showers in breach of a basic rule of etiquette. Afterwards our NCO (MCpl Graves, if I remember correctly) told us it was not polite to either urinate or masturbate in the showers. He used other language of course.