There's no problem with test #2 because the docs clearly show one should use before instead of end if you want test #2 to be consistent with test #5.

Agreed. The inconsistency arises when looking only at the times, and ignoring the open or closed state of the spans -- that was my mistake.

The problem arose when creating recurring start and end sets, and turning them into spans with DateTime::SpanSet. Its docs don't mention that the from_set_and_duration method creates open spans, so that's where my confusion began! Alas, its from_sets method also creates open spans.

Now that I know, it's not really a problem. But I'm still curious to know why open spans are created by default -- there doesn't appear to be a way to change this, and perhaps for good reason.