ME: So there's a struggle?
DIRECTOR: Yeah. I want the blood to hit the wall.
ME: What side of the neck does she get stabbed in?
DIRECTOR: Ummmm... the left, I think.
ME: How are they positioned in front of the wall?
DIRECTOR: No one is by the wall.
ME: But blood hits the wall?
ME: Do you have a storyboard I can look at?
DIRECTOR: Uh, no. I can't draw. But I have everything plotted out in my head.
That was part of an actual conversation I had with a director. After a few more minutes it was pretty clear to me that he had a very set way he wanted his scenes to be shot but lacked any ability to communicate this information to his crew. Ultimately, I passed on the job.
It does surprise me how many people look at me as if I'd just suggested translating the script into Third Kingdom hieroglyphics whenever I ask for a storyboard for an FX scene. I can certainly understand not wanting to bother with sketching out conversational scenes, but action sequences are another matter entirely.
I can't coax a decent stick figure out of a ruler, but I still make attempt to draw out a storyboard for an effect if I don't quite understand what a director wants (or in cases where I've been given license to run the action however I feel would be best.) The storyboards aren't just for me to flesh out ideas on how to shoot the FX, but also so I can convey the details to the camera man and actors. In practical FX, it's kind of important for everyone to know where the gag mechanisms and blood tubes are hidden and how to frame the shot so that they stay out of sight. (Often these gags are moved from shot-to-shot.)
If a director provides me with a storyboard, I can use it to plot out where to hide the gags while maintaining his vision. Sometimes this can be quite a tricky puzzle to figure out, which is why I always ask about storyboards as soon as possible in pre-production.
You don't have to be a great artist to create a storyboard. Asides from the software now available to perform the task, there are several ways to convey the idea in a visual presentation with minimal artistic talent. Stick figures are great for illustrating where each actor is located in the shot. I've asked directors to set up photo storyboards using their children's stuffed animals. My husband takes pictures of jointed wooden modeling figures when planning out a shot.
I know it's a tedious task, but it is also an extremely useful tool when it comes to planning ahead to avoid problems on the set.