Here at the Worx, we often build Drupal websites as intranets. These have on many occasions, become full office automation centers and allow for faster work and better communications. But, they are also VERY custom and require a large degree of testing by the customer as we move towards production.
There are a variety of 'tests' that an application must go through before it becomes production. Most of this is done behind the scenes by the developers as they work their way through the development of your new application.