I've watched 5 1/2 episodes of MY THREE SONS. This was a VERY low-key show. Almost no laughs, and except for the slapstick when the guys are rushing around the house making a mess, not very interesting.
And I guess Fred McMurray was too busy making Disney movies to be on the set every day. He's barely in some of the episodes despite his top billing. The three sons really are the stars of the show.