No Film School has an old article featuring old yet interesting series of interviews with animator and director Terry Gilliam (Monty Python, Baron Munchausen, The Brothers Grimm, Time Bandits) about storyboarding.
From the article:
Gilliam says something interesting immediately, and that is his use of drawing sometimes duringthe writing phase. Storyboards in a strict sense are traditionally done once a script has reached a certain plateau of finality — meaning it may not be locked outright, but only relatively minor alterations will be made in subsequent drafts. Gilliam here describes his storyboarding process sometimes affecting the script as new visual ideas come out, which is an interesting inversion of convention as I see it. He highlights the benefit of using storyboards as the skeletal basis of a scene’s structure, allowing out-of-sequence shooting to work just as well as shooting in-sequence — with some creative variability for how to achieve each frame still retained by the shooting process itself. On the other hand, Gilliam says that storyboarding improves the worst-case creative-scenario, which is running dry on ideas — because even without the in-the-moment idea on set, adhering to pre-conceived storyboards while shooting will still result in a cohesive, coherent sequence.