The first two sub-6.0 episodes are clip shows.

wiki S06E03:

"Another Simpsons Clip Show" is the third episode of the sixth season of the American animated television series The Simpsons. It originally aired on the Fox network in the United States on September 25, 1994. In the episode, Marge reads a romance novel in bed, and it prompts her to have a family meeting, where the Simpson family recall their past loves in form of clips from previous episodes.

wiki S09E11:

"All Singing, All Dancing" is the eleventh episode of the ninth season of the American animated television series The Simpsons. It originally aired on the Fox network in the United States on January 4, 1998. In the fourth Simpsons clip show, Homer claims he hates singing, so Marge shows family videos of musical numbers from previous seasons. The episode is in the form of a sung-through musical, featuring spoken dialogue only at the start and end of the episode. The original material was directed by Mark Ervin and written by Steve O'Donnell. It was executive produced by David Mirkin. It features guest appearances from George Harrison, Patrick Stewart and Phil Hartman, although these are all clips and none of them recorded original material for the episode.