If one does an emerge on multiple packages and one of the packages fails, then all remaining packages are not emerged. For example, I had a partially downloaded mozilla package and wanted to emerge several packages overnight so I entered: emerge evolution mozilla xchat fluxbox evolution emerged successfully, mozilla failed on bad tarball in which user was instructed to delete the tarball. xchat and fluxbox were never emerged because of the mozilla error. This adds a level of robustness to the emerge, allowing administrators to deal only with problem packages (i.e. will allow administrators to start large emerges over the weekend and come back Monday and not see that emerge failed to build most of his packages).
Problem is that the failed package is likely a dependency for at least one other.
