I've been studying such things myself for about 9 months or so and I agree with the essence of what you said.
Not sure what the question is. Are you wondering what approach to take personally? If so, talk to us about your available time budget and cycling goals.
In my own personal experimentation, given my 6 to 9 hour per week time budget and my main goal to enjoy randonneuring (i.e. prevent it from being excessively difficult), I have abandoned my older ways of thinking intervals were the tide that raises all boats and have adopted a pyramidal approach. It's been great. I feel better and have better endurance. I still do some unstructured intensity, but it's only about 5% of my time on the bike, max.