Fans will argue that Mad Men's circularity is one of its greatest strengths.
late 14c., from Anglo-French circuler, Old French circuler "circular" (14c., Modern French circulaire), from Latin circularis, from circulus (see circle (n.)). The metaphoric circular firing squad is attested by 1990.
1550s, "circular figure," from circular (adj.). Meaning "a notice circulated" is from 1818.