If a website is out of the sandbox will all new pages rank pretty highly for their keyterms or does each page have its own sandbox?
What is the sandbox? Basically its a time period that keywords that are competitive must wait in order to achieve results on Google. Is it real? Better believe it. Does the sandbox effect my entire site? No! It is keyword related only. Say you make a site for home loans. Everything about the site is home loan this and home loan that. But you name your site www. doodypants.com. Now you will rank well for the term "doody pants" because it is not competitive. But you will be in the sandbox for the keyword "home loans".
The sandbox is based on the age of your site, not the page - i.e. if your site is out of the sandbox, adding a new page is not subject to it.