New Plastic covers his techniques for getting better renders through render passes.
It’s sporadic in production to get what you need from a single render. Usually, what happens is a lot of touching out and compositing in post. That’s only possible by creating render passes, AOVs, and other image elements.
Check out this tutorial from New Plastic that shows his approach post-compositing with Octane’s render passes and Cinema 4D.
The tutorial uses After Effects and Photoshop to show the two different-but-similar techniques. “Even though I work with Octane, this comping workflow applies to any other render engine; I’ve been using the same method with Arnold and C4D’s Physical engine.”