When a collection is added, it does not appear in the homepage. Instead, you get a message telling you "Update aviable". You actually need to push this message, or drag the page down, to trigger the update.
Why doesn't the page automatically update with the new content?
It feels like an unnecessary action for the reader to trigger the update.
Because we don't want the reader to lose their place. If you're scrolled down that browse page and we detect an update, applying that update could (in many cases) scroll you back to the top which is jarring. We followed the model of many other apps, such as Facebook, where we make it an explicit user gesture so the reader can decide when they want to have their position reset.