It's a given he used his past artwork as a reference, would be impossible otherwise.Yeah, this is Miura being a perfectionist as usual. He probably went back and looked over his old drawings when reproducing these panels. He played around with perspective similarly when drawing Casca's memories. Here are some of them I put side by side for reference, in case some people didn't notice.
That's the best way to use that tag really. For small amounts of text, the inline spoiler tag (checkerboard flag) is preferable.P.S. The images don't contain any spoilers, I just used a spoiler tag to not take up all the space on the page.