why go from intensive tempo to spec 2? that was my question to the board. i don't know? i can tell you that i am not comfortable just "jumping into" speed endurance without some type of acclimation. it just seems risky. what did you do before your 5×180 intensive tempo work?
My understanding is that Spec. End II isn't necessarily more "intense" than Spec. End I, both are done at near maximum (> 90%-95%) of personal best. The primary difference is the distance, Spec. End. I is reps of 150m-300m, more for the short sprinter running the 100m and/or 200m, while Spec End. II, 300m-600m reps, is for longer sprinters who run the 200m and 400m.
For those that do Intensive Tempo (not all coaches advocate IT), the purpose is in fact to prepare the athlete for Special Endurance training. If they have been doing IT training, up to 90% of PB, then it should not be a huge shock to run Spec. End., 90% – 100% of PB, if reps are kept low and adequate recovery is taken between reps.