update: seems to be the case where if raising the max secondary samples makes the image noisier, if I lower the variance threshold/noise level and render it again, it resolves a cleaner image. Still odd that raising max secondary samples would make the image noisier.
Probably a case of the two variances working against each other, raising one limit causes the other one to do less sampling but resulting in more perceptual noise.
Do you still see this when you use uniform sampling?
That was one of the first things I tried. Even with pixel oracle set to uniform I still get noisier images with more samples.
the docs say to have noise level and variance threshold set to the same amount. Even if the variances were working against eachother, aren't the primary samples multiplied (or something like that) with the secondary samples. So I see no way in which increasing max secondary samples could cause lower quality render.
in other render engines, I have only ever had the issue of more samples taking longer (but look better), not more samples giving more noise and taking longer.