Ultra high cadence isn’t necessarily optimal, so as you come closer to a normal cadence, makes sense your RPE is dropping a little. But ultra high cadence does help with certain training outcomes, as does ultra low cadence. Might not want to race at either ends of the spectrum but it helps target “stuff”
There’s a ton of threads specifically about 30/30s, VO2, MAP, repeatability, which often digress into the efficacy of tabatas, sustained VO2 vs on/offs, billat style float sets, hard starts. If you want to do a deep dive into that stuff there is a ton of good information in these threads:
- Look up 30/30s in this thread