This can simple not be true: proof: take 2 computers render in parallel, combine images at the end when happy with the result. The combined images will look bet

This can simple not be true: proof: take 2 computers render in parallel, combine images at the end when happy with the result. The combined images will look better. The 2 computers shared no resources. As such, ray-tracing scales. Luxrender for example has a problem here: all threads are writing to the same output buffer, causing bottlenecks and non perfect scaling. (Might be corrected by now.) The advise then was: run 2 or more Luxrenders, and combine the output image (luxrenders flm file).