Your number of sites, their number of pages, the range of media formats they can support, and the number of contributors you wire into them. Virtualization is a cornerstone of TeamSite. Branches can be set up therein, with their own Staging areas.
Branches are seperate development areas.
Within Branches Workareas are made, kept, and assigned to individuals or groups. Each Workarea contains a complete virtual copy of the site, which gets edited with relative impunity, depending on the user's role, determined by login. TeamSite keeps tabs on assets across the Workareas, and labels all by Name, Size, when they were Last Modified, and by whom. Within a Branch, straying from the pack can only be done deliberately when everything's collaborative by nature. We'll also use it to manage things like our Design Library, which helps us turn our graphics and animations quickly.