For example, let's say a character is tying a tie. If this action is just a little bit of business, not an important part of the story, you could probably do it in just two poses: in the first pose, the character has his hands on the knot -- and then in the second pose, the tie is tied.
But if you are storyboarding an instructional video about how to tie a tie, you may need a couple dozen poses. That's a pretty extreme example, but it gives you a good idea about how to think about how many poses you need to draw.
This is the first of three videos that look at how much to pose out an action. Since there are always a number of different things going on in any storyboard drawing, there are also many other topics covered: staging, silhouettes, using the cutaway shot to advance a gag or story point.
This scene stands out for me as one of the most fun sequences I've ever had the chance to draw... sometimes it's a lot of fun just to get silly. It's also the best example of using a great vocal performance to fuel the drawings; Amy Poehler was on fire when she recorded the track for this episode!
If you missed any of the previous posts, here are the links: