https://manuelmoreale.com/short-long-form
This is something I've been dealing with on my site. I separate my long-form from short-form posts. However, I don't have a hard limit that clearly defines which is which. An initial reason for the separation was, I wanted to have a feed that was easy to scroll through. That was harder to do if I was rendering an entire long-form post as part of the feed. In the end though, most of my posts are all markdown files and their main distinction is how they are rendered.
As I work on my website redesign, I want to change how I think about posts. I want to separate the post content from the rendering. A post is a post regardless of content and length. Regardless of whether it's a response, image, video, note, or anything in between, I don't want to constrain the content of my post. I can choose to render posts differently depending on whether it's being viewed in a feed or individual post page. The content driving those different views though shouldn't change.