Any time I plan a workout I ask… why? What is the goal of the workout? What am I trying to achieve from that workout?
One of the hardest workouts I have ever done, introduced to me by a Swiss National runner, was to do 1k @ 10k pace, 2k @ half marathon pace… repeating without recovery for a total of 10k. All on the track. It was absolutely punishing… but the purpose was preparation for the half marathon distance (for him just over 1 hour). According to him after three of those you were ready to hit a PR.
Your threshold ladder kind of reminds me of that…. But even more painful. So I have to ask… what is the thought process behind this workout?