The challenge is to have as few CIs as possible to achieve the goals of the business. The mantra shouldn't be to zealously reduce CIs and cripple the business -- that is clearly not the message. The intent should be to balance the need of new requirements against the existing defined CIs and try to provision the solution using existing approved CIs.
Configuration Management, a key domain of ITIL that is covered in the Service Support book, is concerned with the tracking of all configuration items in use by the organization and controlling the introduction of new CIs into the Configuration Management Database (CMDB) as well as the controlled removal of obsolete CIs.
Configuration Management is akin to inventory management. The configuration management group, dedicated or at least tasked with the responsibilities, must know what exists, track status and audit configurations in production to their known baselines to ensure that all CIs in production are also being tracked in the CMDB. Savvy IT groups will also use this baseline-to-production comparison to flag unauthorized changes and strengthen both their operational processes and overall security.
Readers may be wondering about the value of tracking all of this data. The answer is that in order for the Release Management team to provision systems and normalize the builds to reduce variation, you must first know what you have. The same for Problem Management teams -- they must know what they are dealing with and so on.
For small shops, this may sound ridiculously easy. Yet, for large shops with more than a thousand servers, this is suddenly very daunting and expensive, but there are very significant benefits to take into consideration:
IT needs to ensure that they have effective configuration management controls and are working to maintain an accurate inventory, normalize the CIs in use and reduce variation. The goal isn't to stop change and advancement. The objective is to simply control the rate of growth of new CIs. Organizations that embark on this journey will see many substantive benefits including cost reductions and improved service levels.