Dumm Comics works as well as it does because it's a collective by professional animators who all know each other and work together and are able to hold themselves to a deadline. In general they're already used to working on tight deadlines, and they enjoy doing comics as a blowing-off-steam-from-work sort of thing; it isn't a second job to them, and when they do slip on their schedule they usually have a hell of a lot of other material they can clean up and post (such as reference sheets or storyboards from their day jobs).
I'm not saying that would be impossible as a thrown-together webcomics collective sort of thing, but it would be... much less probable, say. You'd have to find 5-7 cartoonists who want and are able to stick to a one-post-a-week schedule and that one post needs to fit in with everyone else's schedule, too.
i am a busy bee