IMHO when you switched to the longer intervals at 3 and 4m, they weren’t nearly hard enough. 106% is something you’d be able to ride at for over 10 minutes.
shoot for those 5m efforts at 380-390…every interval is not instant success, especially really hard ones like this. You might only get through two at first, and then 2.5…and then a few months later you’re finally hitting all 5. Meanwhile, RPE is probably going down a touch and before you know it, 400s are your repeat.
It’s a journey!
1x per week…that’s why it’ll take a bit to see the success, but ride z2 and hit the hard stuff really hard, and you’ll start flying.
good luck