When you going to turbine level quantities and potentially non-Newtonian fluids, we already sit down an calculate shit like Reynolds numbers and shear viscosity effects, so I can understand why people prefer the butt dyno.
That's why we pay the Tribo experts so much
But as for me, if you have a good baseline and one oil works well for the car, it'll be fine. The key is to choosing the right characteristics for the right engine, and the best place to start is the manufacturers recommendations. Even with all our lab equipment, test systems and literally a giant oil company behind us, we always start from what the OEM/Vendor recommends and assume it's the best.
interesting way to start a morning (or for me ending, since im on night shifts)
totally agree with you right there and that's what i've done previously and right now.