for the fast-start high intensity interval
I cannot say for certain - most honest answers in training begins with "it depends..."
However, well-trained riders who performed fast-start and varied power intervals accumulated more training time at above 90% of VO2 max when compared to constant power intervals.
Inside this 8 page PDF you will find instructions for the varied power interval and fast-start interval described in two 2019 studies by Bossi et al and Rønnestad et al (1-2).
1. Bossi et al. Int Journ Sports Phys & Perf 2019
2. Rønnestad et al. Int Journ Sports Phys & Perf 2019