It ain't new and it ain't revolutionary. My HS coach (late 80s) and college coach (~90) were Lydiard guys. Volume, 2x per day, often tempo AM (steady state in Lydiard vernacular), repeats afternoon. We NEVER hammered workouts. They were mostly tempo and longish repeats at around 5k-10k race pace. We did long runs every week. Consistency was key. I got faster every year for 8 years under those 2 coaches.
What is different about JI? He started early, has immense talent, focus, drive, and a dedicated coach training for the long term. Very few runners have all those things. I have spoken to some Olympians and their support structure is amazing and consistent over their whole life.
He also may have access to supplements and physical therapy that not everyone does that allow him to push hard consistently without getting injured. I could count on one hand the number of sports massages I got in college. JI probably has someone available every day. He likely has his blood tested regularly and gets appropriate supplements.