TB HV3 Recovery Week Supra Threshold

So, I have been doing base training for the past 4 months now and I am at the last week of TB HV3. The first workout of recovery week is Mt Hale +3 (supra threshold 4x9 min @105%!). I haven’t done any supra thresholds workout nor have I seen any in the whole TB plan, then this!

As you can see here, I failed the workout. I did a 4x9 min the week before at threshold (which is a very different zone, I know), so I would have expected the interval duration would have ramped up to 9 min for 105%, rather than starting with that duration. Maybe the fatigue from the week before contributed, but rather than finding excuses, I am wondering how I c

Curious what the rationale is for supra threshold of this length after extended duration with no intensity at that level. That’s not to say the rest of the HV3 plan is not hard, it was challenging but very rewarding.