When was the last time you were there? I went in 2019 and 2020 and it was really easy to get around. All stations have signage in English almost everywhere. Google maps says which exit / entrance to come in or leave from, even which car of the train you're on is closest to the path you need to get off.

As for walking, you don't need to walk _everywhere_ but it really is cool to spend a few hours like OP said and just walk around your hotels neighborhood or other places.

I usually stay in Higashi Shinjuku when I visit, and if I hadn't done that I wouldn't have known about this really quiet residential area that leads to a nice quiet park. Or the little Korea town neighborhood that's about a twenty minute walk away.