In 99 % of the projects, we only have a single repository to build. But to make the configurations as generic as possible (so we can easily clone for new projects), we define the following variables for all configurations:
RepositoryUrl => $Source.SomeRepository.Url$
RepositoryPath => $Source.SomeRepository.Path$
RepositoryBranchName => $Source.BranchName.Path$
RepositoryName => %ProjectName%
Would you feel something of “simplified variables” such as the ones above in case you use a single repository => these values are filled. In case of multiple repositories linked to a configuration, you can fill the values with “error - this only works with single repositories” which should provide enough info to the user.