From an Onion AV Club interview with Mad Men's Matt Weiner:
AVC: As a show-runner, what level of oversight do you have? You say you not micro-managing as much...
MW: Well, the people who work for me may laugh at that. [Laughs.]
AVC: How much of a hand do you have in, say, the episodes where you're not a credited writer?
MW: Every single word that's on the screen, I oversee. There's nothing that's shot, I'm not involved in. The scripts go through multiple drafts, and I work with the writers on all these things. And I'm extremely involved in the writing process. As far as casting, I'm there for every single person that's cast. Even if it's one word, I'm there for their auditions. I'm involved in the props, a lot of which are written into the scripts. I'm involved in the costumes, which are all shown to me before they go on. I write some things in, but it's another one of these things where it's like, at this point, [costume designer] Janie Bryant comes and tells me "I'm doing this," and unless I hate it, we do it. But I'm involved in it. A lot of it, these details are written into the scripts. The scripts are very specific. What kind of drinks people have, where they're sitting, those kinds of things. I'm involved with the directors. We have tone meetings where I explain to them the script, page by page and word by word, and often perform it, which is embarrassing but true. I do a great Joan. Then on the set, I visit the set for a lot of the rehearsals, and there's always a writer on set. And then I'm involved in post-production, very intensely involved in editing, and the sound mix and color timing. Really, I have about nine jobs.