A very prolific harmonizer of Gregorian chant in the early 20th century was Mr. Julius Bas. He often uses a very strange technique, wherein he employs rests to eliminate the Alto, Tenor, and Bass voices. Consider what he did with “Lumen ad revelationem” here:
* JPEG • Lumen ad revelationem
It seems quite lazy, and I’ve never seen anyone else use such a technique, although Dr. Peter Wagner often switched to parallel octaves when he ran out of ideas… (Yuck!)