Now
Bread and Circuses is one I love and consider a top class episode. Since the parallel Earth development was baked into the concept as an attractive pitch to save money, these stories were inevitable. But grouped together, they can lose punch and feel tiresome. The second season really had a lot of them (like 5 in the back half). But B&C was filmed much earlier than its airdate.
This is one of Roddenberry's better scripts with great snarky jabs at network TV production. The side characters are all well done and the climax is thrilling. Great cast all around.
I'm totally fine if newer Trek doesn't revisit these concepts, but to each their own. However, SNW's primary focus is to apparently re-do TOS concepts, so it'll probably happen anyway. Y'all can let me know.