Quick, I have never used such an approach so I cannot comment from personal experience.
However, what perplexed me about the examples of progressions posted here was their enclosedness to one particular distance and rest periods per week. Perhaps you could soften the progression jumping from 50 to 80 in one week by introducing different distances in one training session throughout the whole period.
So week X would not have to be 3x3x60, it could be, for example 3×80, 60, 40 (the rest period for each distance could also vary). This way you could perhaps have a smoother progression between weeks, and by altering rest periods between runs and sets you could manipulate the desired outcome on a volume vs. intensity scale.
i dont think ur example would make a difference.