During the development of packit project, we have gathered several user stories:
DNF project: it is composed of several repositories which need to be built and tested as a unit.
python-maint: a common big task is to fix and backport CVE fixes.
Fedora rust SIG: these guys have a tool to generate a spec file which can be used for every new upstream release.
Multiple packages (read SRPMs) in a single repository.