Hi Thomas, as always excellent words, I agree with your reasoning.
However, the only thing that I would like to underline and point out (which perhaps you haven't taken into consideration) is that the scene has a resolution of 1600x900px and not 4K in addition to the fact that if in a 7950x it takes 6 minutes to reach the 5%, in a normal workstation it definitely takes half an hour.
Also add that the scene (corona academy course) is composed:
- corona sun and sky (no additional hdr or artificial light)
- colored side wall
- there are no windows or other objects outside the sofa taken from cosmos (e.g. windows or other)
- the rest of the room has only the default crown material
.. this is exactly what it honestly seems to me is very anomalous and leaves me wondering given that the success rate is almost 90% and therefore at the maximum for the calculation and processing speed.
In any case, I did the required tests (1600x900px) with today's latest release (something has improved but only slightly):
-limit set at 50 passes, the render takes 3.09min and stops at a noise 6.70%. The scene is too grainy despite having activated denoise with radius 1 and amount 0.65.
-limit set at 5%, the render stops at 90 passes taking 5.49min and with the help of the denoise radius 1 and amount 0.65 it turns out quite clean.
Test render 3072x1728px with stop render set at 5% takes approximately 23min (if I were to hypothesize a 5 second video at 30fps it would take 55 hours with my workstation with 39 thousand cinebench points).
