I’m a fan of putting it all onto the page, messy chaos and all, when you’re in the early iterations. So much gets lost when you keep it in your brain, especially as you get older (*sad sigh*). I try to jot things down as fast as I can in the thumbnailing stage, even if I have done a preliminary script prior.
It is incredible how much is revealed when you put things down on the page. Flaws come forward more easily, strengths shine through that you didn’t consider… it’s a crucial stage that I didn’t appreciate a few years ago. I’d just put panels down in pencil and see what happened, and for better or worse, I kept whatever I put down.
As I get older, perhaps I’m getting more cautious, and I like to plan more of where I’m heading. Thumbnailing lets me try out some messy concepts without being too committed to a panel I spent a while pencilling. It’s a bit embarrassing that it sounds so obvious to me, now, to write this out and be like “gee, thumbnails are great!” but I think a lot of us gloss over it as an optional or annoying extra step. It’s really not!