In my many years of watching sitcoms, there have been a few that have used the same director for almost every episode. The two that come to mind are Happy Days with Jerry Paris and Green Acres where most of the episodes were directed by Richard L. Bare. Any other sitcoms that used the same director for the bulk of their episodes?

Father Knows Best: seasons 1 and 2 were directed by William D. Russell (there are incorrect credits posted to some early episodes, esp. for season 1) and seasons 3 thru 6 were directed by Peter Tewksbury.

Mama's Family: the syndicated years (6 seasons) were all directed by Dave Powers.

Hazel: the NBC episodes (4 seasons) were all directed by William D. Russell.

The Adventures of Ozzie and Harriet: No good source for this, but I think Ozzie Nelson directed all 435 episodes.

William Asher directed 131 of 254 episodes of Bewitched - and 100 of 180 episodes of I Love Lucy

Minus a few episodes, seasons 2-7 of Diff'rent Strokes were directed by Gerren Keith.

Doug Rogers directed all (38) episodes of Hello, Larry.

David Trainer did every episode of That '70s Show except for the first two.

I think all the Flintstones, Jetsons, and Top Cat episodes were produced and directed by Hanna and Barbera.