First, it’s important to define each situation. A single site is defined as a standalone production site. A single site plus site extension has one main location for production but extended workshop occurs from a separate site. A corporate scheme is a group of several production sites that are centrally managed by one quality management system (QMS).
The primary benefits associated with using a corporate scheme standard as opposed to the other two options is that there are some allowances for a reduced auditing time and harmonized auditing process. The organization can run all of its production sites according to a multi-site certification plans as opposed to every production site having its own set of policies and procedures. This is reflected in the auditing process — the organization is reviewed centrally to maintain harmonization.