Like no, obviously I don't think the writers of the show sat down and talked explicitly about the Goddess triune when constructing their Opera House, for example. But it works out, of course, because that's how stories work. They tell self-organizing truths, just like we all do. But speaking as a writer, there's a certain give-and-take with interpretation and the facts. You'll only ever hear a writer say, "That's amazing! I didn't even intend that!" Point being, I'm going to keep the amplification to a minimum this week, and try to stay a little more focused on the facts on the ground and the imperatives that brought them about. I'm not trying to Cavil you: you're free to think whatever you like, regardless of what some dude on a website says about it. On the other hand, I think it shows the areas of our blindness when we throw away a toy instead of figuring out how it works.
Though you'd really be surprised how much of that stuff is actually intended and iterably true. The people who write this stuff think about it more than you do. And I don't think my track record would be as good as it is if we weren't at least sometimes on the same page with this stuff. Think like a writer, not like a passive consumer. Some of it's the blueprint, and some of it is looking back at the historical record of past episodes and seeing the paths they could follow, and discarding them one by one until the obvious-but-still-interesting solution presents itself. In the case especially with Final Season-itis, and I could give you approximately a billion examples from Sex & The City to Once & Again to Dawson's Creek and The O.C. (the easiest ones to see because of those show's reliance on Jungian typology), there's a mandate that must be followed in order to finish the story: everything turns into its opposite.
What's the first article of faith? "This is not all that we are." Samantha loses her sex drive, Charlotte marries a Jew and adopts an Asian baby, Miranda gets saddled with a very sudden and very demanding family, and Carrie leaves town: everything must turn into its opposite, for the same reason that the first colors in alchemy are black and white.