I am wondering if it's possible to change the sampling or otherwise the render quality per object in a scene.
The use case is if I know an object will appear essentially the same with lower sampling quality, but other parts of the scene will take higher sampling to look good.
Example: I have a cloud object on the left side of the scene, requiring volumetric calculation, greatly increasing the amount of render time for the whole scene. On the right side of the scene, there is a simple box with a diffuse shader, requiring no volumetric calculations. So because of the cloud, the whole scene takes much longer even though it's the only thing requiring extra calculations.
I supposed the current solution would be to render the parts separately (left, then right), then stitch them together in PS, but I'm hoping there's a better way to do it more selectively and precisely and within Blender.