There will typically be new content of some kind appearing weekly! However, since many Neopians live busy lives, you won’t be penalized for not visiting every single day new content is released.
Content will be released in the form of Chapters spread over three-week periods, during which everyone can still catch up on content and collect full rewards! It’s only after each chapter ends that you will lose out on exclusive prizes. So you’ll want to make sure you are all caught up on the last day of every chapter!