Submax sprinting is a better way to maintain form through out a speed endurance run. If you are going at your absolute threshold for maxV for repeat 120s for speed endurance (or any other SE distance for that matter), good luck at making the workout a quality one.
No one is arguing for submax MaxV work. But in order to develop speed endurance concurrently with MaxV, you need to ease off the effort that 5 or so percent on the SE days.
edit- I should say no one is arguing for ONLY submax MaxV work. I’ve had good results early on in my first MaxV cycles using slightly submax effort.