The considerations that apply to system change management make compelling arguments for applying a consistent process to change management, so that all the considerations are consistently addressed.
Advance discussion of a proposed change gives people the opportunity to consider whether the change is necessary and think about its implications.
Developing an implementation plan usually means that you can do the real work more quickly, which can be important if something has to be taken down to implement a change. A good plan also covers a couple of major areas:
A complete process should include all of the major issues: communication, documentation, planning, implementation, testing, and if necessary backout. Having good tools like RCS can make these steps easier; RCS can be used both to make documentation more automatic, and to allow for backout by retrieving older versions of files. Backups (both system-wide, and as part of a specific implementation plan) also make undoing a change faster and easier.
In a larger environment, you may have parallel systems for development and testing that are distinct from the production systems. Changes can be tested and fine-tuned on the development systems without affecting the production systems. When a proposed change is working in the development environment, it can then be implemented in your production environment with more confidence.