Naturally, commentators read commentaries, but at times it seems like more than that, e.g. on Eph 5:6:
(a) "This suggestion has the merit of maintaining the ‘insider/outsider’ contrast that runs through the passage."
(b) "This interpretation also maintains the insider/outsider contrast that runs throughout the passage."
(a) = Peter O'Brien, Pillar New Testament commentary (Grand Rapids, MI: Eerdmans, 1999), 365.
(b) = Andrew Lincoln, Word Biblical Commentary (Dallas: Word, 2002), 325.