Quote -   What if someone  happened to stop their render too soon because they were too impatient...and then realized after calming down that the image really did need more time, maybe quite a bit more.  It could happen right? 

This is a built-in feature of Lux. Simply start Lux and File/Open the scene exported by Reality. Lux will restart from where you left off. Do not re-launch the rendering from Reality, that will restart from the beginning. Just launch Lux by itself. You don't even need to start Studio. This and other features are described in the Reality User's Guide.

Hope this helps 

Paolo

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