4D and Half is Easy: Is AC more like FTP?
Half is Easy (HiE) vs Standing Starts (SS) vs The Trick.
It looks to me like 4D is just going to scale different parts by your 4D power for the corresponding effort length.
But then are HiE intervals about your ability to produce power for 15 seconds, like in SS, or even a minute like in the The Trick or in the Full Frontal test itself, or are HiE intervals about the ability to recover quickly from anaerobic efforts and maintain a sort of long term average (normalized) power over many efforts? In HiE I keep an eye on my heart rate (and previous attempts at the whole session) to pace the intervals so that I'll just suffer through the last one. In SS, I'll just go all out every time, so they seem completely different to me, and I probably don't really need 4DP for either one.
Interestingly the 4D profile for SS says it's mostly NM, but the sprints are mostly in the AC category. I suppose that could all be right depending on how you look at it.
Personally I get used to what I can do on particular intervals, which isn't to say I wouldn't benefit from a customized plan. That's different. It doesn't help that the underlying processes and limitations still seem very uncertain. I don't think normalized power is anything more than a guess that kind of works, and it's hard to believe the same guess works for averaging over-unders and also for endurance to tempo shifts.