Parallelize all operations that are OK to parallelize (like installing, uninstalling, upgrading, etc. multiple apps in parallel).

Should anything not be parallelized?

When errors occur for parallel operations, I assume that all operations that can succeed should be let finish, then all successes & all errors should be reported together, with normal info output to stdout and error info output to stderr.

PromiseKit: when(…)

Swift Concurrency: async let, TaskGroup & withTaskGroup