Depends on the specific site and use-case I’m sure. My initial thought was that it would be more likely for a site to want it implemented everywhere, and if there were exceptions it would only be a few.
If you wanted to implement a banner for a small number of categories there might be a better theme component option that’s built to be a less generic cover-all, like Versatile Banner or customizing one of the options found in Banner themes (and instructions for customizing them)