This integration process requires the replacement of some parts of the operating system with customized configuration files or even the integration of whole new features. These changes have to be performed during the initial installation of the machine but may also be necessary after changes to the local environment and if updates or security fixes have to be integrated. At the simplest level this customization is done by hand on an individual, per machine basis. Cost is high because highly skilled personnel is required to perform repetitive and tedious tasks. Documentation of the customization is often poor because it is at best in the form of an installation log.
Clickable interfaces are the worst when it comes to documenting what has been done.
The approach scales linearly or wors if the growing likely hood of inconsistencies is taken into account. In other words automation of the post install process is imperative for large installations. An simple approach taken by many is to write a special customization script which is run on a machine after its installation. Customization itself can be a complex venture. With an all dancing all singing customization script the script itself becomes huge and unmanageable.