Unless they've changed since I left in 2005, NTPS in Mojave didn't use the 6 (or 7) part paragraph with any seriousness.
Well that can't be right; the use of humour in technical writing should be discouraged...
Here at ETPS, we teach the 7-part format as an aide memoir rather than a straightjacket. It
mirrors the flow of effective human communications: set the scene, present information, and then make your point. The result is a logically built argument that's more likely to achieve the desired effect. So the format is not an ETPS invention; the means of describing it as a ready 'checklist' may be.
It's certainly not rocket science - that's ground school!