That is a grey area but let's call it what it originally was called Hyper sync. That version of sync causes you to lose tremendous power out of the strobe, flash duration and will eat through your VMLs quicker. In a sense, it's a work around but not a solution if you still need maximum power and short durations.
We really need to stop calling lights with long durations and tuned to cover the time the shutter blades are exposing the sensor HSS, the two work in a fundamentally different way, long duration is not HSS, and both cost a massive amount of power.Hah! Interesting point. HSS...strictly technically no but practically yes. What is it that defines "true HSS"?
We may have strayed from the strict HSS definition, but it's a useful terminology that people understand.
Think of it as living language. The acronym HSS communicates a function....High Speed Sync. Simple enough.
So what do we call it? We're achieving flash sync at a high shutter speed. We understand the limitations such as significant power loss, but it's still a very useful, relevant creative tool. Sounds a bit HSS-ish to me!
True high sync speed out of a x100/leaf shutter cameras is actual HSS. One pop within the full opening of the sensor and closing at above normal sync speeds.
Only if the flash duration happens in the time that the shutter is fully open, which at close to full power is never the case. Leaf shutter sync above "normal" speeds relies on very short flash duration. It is easy to prove because raising the flash power won't increase exposure (or even worse uneven exposure/heavy vignetting), leaf shutters work like an effective second aperture.
And I'd probably disagree with your definition of HSS, because it isn't "one pop within the full opening of the sensor", HSS is multiple flashes timed such that the exposure is even across the frame. I am not looking for a fight, just laying out the way it works.
I think the key is the difference between relying on very long (hypersync) or short (leaf shutters) duration flash, and pulsed "HSS" flash via modern IGBT circuitry. Hyper sync relies on long flash duration and no flashes give off even light across the duration of the exposure, though it is often even enough to be good. Leaf shutter sync relies on very fast flash duration which doesn't happen with high flash outputs.
This core difference in newer and older flash tech is where so many doors have been opened, but they have been workarounds and kludges. The plethora of new battery powered "studio" strobes like the Profoto B1 and the Phottix Indra 500 TTL, a Yongnuo version etc, all have genuine HSS IGBT pulsed flash capabilities, as could the Einstein if PCB ever decided to write the firmware.
Hyper sync - long duration flash over the entire curtain movement
True high sync speeds - standard sync method but @ above 1/250th. (Which is still the best and most efficient but expensive.)
HSS - pulsed flash over the duration of the curtain movement.
I think you misread my comment, all of these methods are ways of syncing at High speeds, hence HSS but the most true form is the traditional method and the others are a workaround.