There is an episode of American Dad! where Roger is an acting coach. At one point, he gets worked up into a rant about acting and randomly shouts at a student to bring him butterscotch. The student asked what kind of butterscotch, but Roger simply shouts for her to go. Roger continues his rant about acting and the student returns with her arms full. She says that she brought butterscotch candy, butterscotch pudding, and butterscotch ice cream. Roger grabs the pudding and smacks the rest of it out of the students arms. He smears a handful of it on his face and shouts out, "Pudding Man!"
There are a few seconds of silence. Roger regains his composure, then calmly asks to the class, "Why didn't that work?"
I actually found it to be a very interesting scene. This character gets wilder and wilder, which is increasingly amusing, but then he does this one action which goes too far and completely loses the crowd. It is an undeniable fact and no amount of trying to hide or cover it up will change that. Rather than try to justify it, he accepts it and uses it as a moment to reflect and to teach.
Why didn't it work? I started thinking about it. Pudding Man had no context, so it existed in this vacuum, which took away its power of relation. Where Roger was previously irate, Pudding Man was campy. This complete shift in tone and feeling and sense completely derailed the scene and jars the audience. That utter confusion loses the audience, along with their laughter.
The only reason I analyzed that scene was that Roger told me to. He posed the question and forced me to think. There is no exercise I can think of that is more beneficial to a writer's growth.
In fact, my college professor had us do exactly that. Understanding why things are effective is great, but all too often we ignore our failures. We say "it doesn't work" or "it doesn't feel right." These are not helpful answers. They are leads to go hunting for real answers. Follow those leads. Be able to explain your failures. Be able to explain other people's failures. And do so with concrete language.