In studying a number of “high-performing” IT organizations, the authors of The Visible OPS Handbook: Implementing ITIL® in 4 Practical and Auditable Steps (Behr, Kim, & Spafford, 2004-2005) found these organizations shared a common philosophy which states “the only acceptable number of unauthorized changes is zero." It is this culture of change management which allows these organizations to perform at very high levels as measured by:

High availability (high MTBF and low MTTR) 

Change success rates over 99% 

Less than 5% time spent on unplanned work 

Server to system administrator ratios greater than 100:1

 

Link

Automated Change Management in the Data Center