Page One meanwhile leaves the site design in place (in most cases), letting you see the article’s entire content without breaking from the site’s browsing experience. You don’t have to take any action to trigger Page One’s functionality, either. It makes its changes silently so that you’re getting full content as part of your casual browsing.
the way that the extension works is that it silently changes URLs for multipage articles to those of publicly available single-page or print-friendly views. In other words, for me to support a site, it has to have public a single-page or print-friendly view.