When A uses C, and B also uses C but another copy of a different version, that can create problems that would have been avoided by doing the planning work. Not

When A uses C, and B also uses C but another copy of a different version, that can create problems that would have been avoided by doing the planning work. Not only are you exposed to two sets of bugs in C (some of which are already fixed), but C may not be fully forward and backward compatible with its own output (especially in-process).