I don't know where I heard this, but the last three seasons of the show should have been called, "Let It To Wally".
Yes, they just finished airing the last season's episodes here on a local channel and I noticed that "Beave" was shoved into the background in many episode story lines as the Cleaver's concentrated on Wally's and his friend's problems - getting a cars & driver's licenses, staying out later on dates, graduating from high school, etc.
Do you remember the opening credit actions?
Season 1 - animated with the camera moving up a sidewalk with obviously wet cement and the credits written in it.
Season 2 - June and Ward stand at the bottom of the stairs. Wally comes down, gets his school lunch bag and leaves. Then Beaver descends, gets his lunch, puts on his cap and leaves.
Season 3 - Ward and June enter the boy's bedroom where they are asleep and wake them up.
Season 4 - June and Ward emerge form the house and stand on the front porch as Wally, the Beaver come out. The parents hand the boys their books, lunches and jackets.
Season 5 - Ward and the boys are outdoors doing yard work, Ward trimming the hedge and Beaver and Wally mowing (why they need two mowers for such a small yard is unknown). June emerges out the front door (which mysteriously opens for her and closes behind her) carrying a large tray with what looks like iced tea or lemonade and offers it to the guys.
Season 6 - June comes out the front door all dolled up and heads for the car parked in the driveway. She is immediately followed by Ward carrying a picnic beverage cooler. Then Wally runs out carrying a wadded up towel and gets in the car. Lastly, Beaver runs out and gets in the car as Ward backs out the driveway. This opening also had a jazzed up version of the theme song.