Just curious if there is a way to use an RE pass while rendering to determine where I should focus my Region Render areas? It seems the best indicator currently is the beauty pass, thought the Cinfo_SamplingFocus would provide info for that purpose.
On quick renders, I’ll use the intel CPU AI Denioser, then region render the noisey areas. I decent work around is to ‘Save CXR’, see the noisey areas, then ‘Resume’ and focus the Rengion render on those areas.
Sampling Focus is the closest thing that will exist for that. Mostly though, it will be a visual thing determined by the viewer anyway as to when any remaining noise looks “too much” or not. There probably isn’t a way to say what is noise, and what is (say) bump map or texture detail - if there was, then it would likely be possible to have denoising that easily focuses just on actual noise vs texture detail 
Fair enough, I guess that would solve any denoising problems, if it were distinguishable. lol