So I had a little project where I had to create captions and have my character fit those captions. I am posting just a few of the ones I did to show how drawing out thumbnails on paper really help your poses because you may have the idea in your head, but unless you see it, you are just guessing where everything should go when you put it together in 3d or a more detailed 2d drawing.
Thumbs are a quick way of getting your idea out and you don't even have to be neat with it. As long as you or whoever they are meant for can read them, they can be almost chicken scratches like the ones I have.
If I had not drawn these out first, my poses may not have come out as strong as they did. You can see I also tweaked some of them for the better.
Your poses don't have to match your thumbs 100%, because the thumbs were just rough ideas. You need not waste your time rendering every shadow or every detail, the drawing or render should be the polished final.