i think the main reason why season 4 didn't work is because how they separate the characters from each other. the funniest and most favorite thing about AD- to me, however, is how all the characters are self-centered and really isn't fit for a family. but they have to, and the result is disastrous. Plans don't collaborate and create hilarious moments. the chemistry between the actors are also phenomenal, most importantly the characters complete each other to make funny scenes. so, when they separate the characters they literally lose a very great element to the show.