What might be worth doing is sending three different sampling approaches to the farm and picking which comes out best - one favouring low aa / high samples on all else, another on high aa and low samples and a final one on medium aa (say 1/12) and medium samples?
oh, I was thinking of something a lot simpler, John.
Ignore the render settings completely.
Adaptivity becomes prominent, and often undesired, at extremely low lighting levels (within, or around, the noise threshold, to be precise).
So rendering an image with an arbitrary setting, lit to produce colours around 0.5 float, and the same, but to produce colours in or around the 0.01 float range (or lower, although it wouldn’t really make much sense for it to be too low in Arnold, or other renderers), SHOULD lead to a faster, and grainier result.
If it takes the same amount of time, and it’s just as noisy when normalised to the previous image, then you have no adaptivity to speak of.
Sorry Lele, should have quoted Dmitry there, was more a scripted approach to getting good settings. Must resume email chats on quality and theories though!