I used a hybrid method.
Ford and many other companies use a Torque/Angle sequence, with or without TTY. Torque has a lot of scattering, and in the engineering world, it's typical for a factor of 15% variation to be expected in the tension, even with lubrication. Torque wrench accuracy is on top of that.
The biggest reason for using the angle method, you rotate a thread a certain amount of degrees, and the bolt is stretched how many threads have been advanced. There's no variation. You have a 1.0mm thread; 360º stretches 1.0mm. The exception is when there is a compressive element or inconsistency in flatness between the objects. And we have that with a gasket.
So the 6.0 procedure developed was to use torque to set the base or 'floor.' Torque as measurement will adjust for the bending and compression of components. When done at a lower compressive condition, the lower torque, the 15% deviation is not much of a factor.
Then you come at it with the heavy hitters, the angular stretching of the bolts, after you've set your floor.
So I set my floor following Ford's initial torque values, then did three steps to the ARP torque steps. What the ARP lube has going for it is the unique ability, more consistency than the standard oil because, from what I can tell, it does not allow the threads to get polished. And thread polishing not only affects reuse tension values but consistency fastener to fastener. Since torque is a measurement of movement force, frictional variation causes that 15% scatter.
With studs, you should have minimal tension loss due to twisting the fastener's shaft, as long as the threads have low friction. There is still some, but not like a bolt where the rotation is transmitted from the head, the shaft, and the threads. Eventually, that unwinds to some degree. If it's head rotation with a bolt, then no issue. If it's thread movement, it unwinds with a loss of tension.
So with the studs, it's essential to keep the rotating surfaces controlled, which should be the top threads, the nut face, and one washer face. So that's where my lube went to. You don't want the washer to become a bearing, so no lube between the washer and head if it's smooth. I had a discussion with ARP over this on our engines, and the guy really didn't know what our head surfaces were like, to say if the washer to rocker box should be lubed or not. Another example is that these are fastener experts but have no individual engine detailed experience. But he agreed if the stanchions through the 6.0s rocker boxes are smooth, there should be no ARP lube between the stanchion and washer.
Another variation in tension that occurs during fastening is the compression of asperities. That can be in the compressed objects: washers, nut faces, and threads. With critical fastening, a good procedure is to step away and let the recently tightened object sit for about 30 minutes before the last step. Thread asperities will be at both ends of the studs. Some talk about waiting hours or a day, but the engineering studies I found said 80-90% of any loss of tension occurring from this is during the 30 minutes after the step is complete. That might even be in Shigley's Mechanical Engineering Design.
Even if you go back, loosen the assembly, and retighten by torque, you will not get back to the same point of asperity compression. So the last step is a wing-it. The non-rotating surfaces already have their crush, including that non-rotating washer.
I did the 30 minutes at the final step.