Nice and good to know, nice find.
This is very handy:
Though still it is not clear (to me) if there are any particular advantages to this format (outside the very narrow scope it seems to have been developed for).
The whole idea of a "gang programmer" is entirely new to me, and - as always happen with MS documentation everything and the contrary of it seem like being "detailed" (in the most confusing and vague and contradicting possible way).
(please note how this is not in the "desktop" path but rather in "mobile" - while still under "manufacture"):
Each manufacturer has different techniques and tooling that they will use to manufacture and service a Windows 10 Mobile device. The best technical expertise regarding manufacturing resides within those who built the OEM manufacturing line. This means that the OEM will need to determine which flashing and manufacturing process will work best for them. OEM service centers may have unique needs that will also influence the selection of flashing tools. The OEM will need to determine how to test and validate that the selected tools and processes meets their cost, quality, and other unique manufacturing objectives.
The OEM uses the Microsoft supplied imaging tools to create the FFU OS images that are flashed to the device.
The Microsoft provided FFUTool full flash update (FFU) technology is designed for engineering development, and testing purposes; it is not supported for use in manufacturing.
So, in an article dedicated to mass manufacturing, they suggest to use a tool NOT INTENDED FOR MANUFACTURING and to the intended audience (highly experienced hardware developing and manufacturing engineers) besides some generic "do the right thing" suggestions they add these pearls of wisdom as caveats:
FFUTool known issues
Using the FFUTool has a number of significant limitations that are summarized here.
USB hub activity may cause flashing failures
Some USB hubs have been known to cause reliability issues even when flashing devices in serial due to hardware interference to the streaming FFU data.
Multiple devices that share a single USB hub cannot be connected and disconnected while other connected device are flashing. This uncovers a known hardware issue with some USB controllers. For more info, see KB908673. You should not unplug USB devices when device flashing is underway.
USB cable length is limited to 3 feet
Flashing may be less reliable when using USB cables longer than 3 feet (.91 meters), or if your flashing setup contains consecutive cables that total to more than 3 feet. This is due to hardware limitations of data transfer in longer cables.
Flashing time per phone
You will need to evaluate whether the flashing time per device meets their objectives for your manufacturing line.
It is still good ol' MS alright.
I'll add a picture: