How to group test cases for multiple runs (multiple test cycles)

It looks like test cases can be assigned to a release or iteration, or test cases can be assigned to a test set.

What's Inflectra's vision for how this is done?

I would like to be able to look at my release page and the column Test Coverage and quickly see how many tests have been passed, failed, cautioned, blocked, and not run.  

If I have multiple iterations in a release, each for a different and parallel set of functionality, should each each of those iterations have one child iteration per test cycle/run for the parent iteration?  That would seem to provide us with the view we want.  (It doesn't necessarily use Test Sets at all, for better or worse.)

Thoughts?