Short intervals are one of my favorite workouts. Maybe other also use this and we can share some experiences.
Billat demonstrate that with intermittent exercise one can work very long time on V02max
https://www.researchgate.net/profile/Valery_Bocquet/publication/11982450_Very_Short_15_s_-_15_s_Interval-Training_Around_the_Critical_Velocity_Allows_Middle-Aged_Runners_to_Maintain_VO2_max_for_14_minutes/links/0c960521462f8665e8000000/Very-Short-15-s-15-s-Interval-Training-Around-the-Critical-Velocity-Allows-Middle-Aged-Runners-to-Maintain-VO2-max-for-14-minutes.pdf
Later Rønnestad compared short and long intervals and found superiors adaptions.
The 30/15 High-Intensity Interval Session A practical guide
The Group around Seiler made a similar experiment and found difference to long intervals. The experiment is mentioned here at page 19ff
https://www.researchgate.net/profile/Stephen_Seiler/publication/320592077_Session_3_Interval_training_prescription_physiology_and_perception/links/59ef4716aca2721ca5e9325d/Session-3-Interval-training-prescription-physiology-and-perception.pdf?origin=publication_detail
As far as I know the experiment is still unpublished ?
An interesting approach is to perform the short intervals with decreasing power. This is again based on the work of Billat
The sustainability of VO2max: effect of decreasing the workload.
I tied this approach but I’m not sure if hard start is a good idea. Is very demanding and therefore it needs longer rest periods between the series. Maybe the overall RPE is also higher. However maybe once reached a high fractions of V02max, it might made send to decrease the power a little bit. This may enables to make one repetitions more or shorten the series rest.
But this is just that I’m thinking about and I’m unsure