If you compare the 250 to the 200m PB it’s more like 85% speed for the actual rep distance (extrapolating that she’d drop off a little from 200 pace for a 250). She did this workout for 3 weeks. Week 1 was 40-42 and she was only able to do 4 and she’s a tough cookie (roasted: drowned in lactate if you will). Week 2 she hit 39-41 and did 5. Week 3 was 37-40 with 5 reps the day after a race. Looking at her times and program she was begging for this kind of work and had the support qualities for it. She needed more training so we dialed it up. Hence the rapid improvements and adaptations.
Linas brings up an interesting question with event dynamics changing training. Should the training be the same in terms of distances and percents for a 56s 400m high school girl and a 46s collegiate male of same training age? I think the answer is yes you’d see a lot of similarities, but adjustments to account for longer event duration and tweaks of distances covered in certain general physiological/performance windows. Development (training history/skills/age, chronological age, and current skills and areas of adaptability), and physiological time frames (15s for pure speed endurance for example) for certain training qualities play a role in the adjustments beyond just event duration.