VC is not a total solution to the project-management problem. Although it assists single-author programming or document maintenance greatly and can give vital help on small- to medium-scale projects involving several developers, it's not necessarily adequate by itself for large multiple-component, multiple-directory projects. The following are some of its more obvious deficiencies for larger projects:
It is not integrated with a change request or problem-report system.
Its only way of grouping project files is by directory subtree. This limitation may create problems for large, multiple-directory projects, especially when two or more need to share a common library or subtree.
You can work around these deficiencies on small projects. Variant versions might be handled with compile-time conditions, like #ifdefs in C code. Change requests can be kept separately in some kind of database (such as the FSF's GNATS system, or Mozilla's Bugzilla). Programmers can carry around in their heads the state needed to do renames without disruption.
As projects scale up in size and intricacy, however, such ad hoc measures increasingly fail to prevent damaging friction and lead to death by accumulated details. Complexity control for very large projects requires a fundamentally stronger (and, unfortunately, more constraining and complex) support environment that goes beyond version control—a full project-management system.
For more on the design issues in project-management systems, see the ...