Checked with version: 2018.1
Optimizing lighting is an art, not science, but you can influence it by carefully managing your Scene settings.There are many parts to creating a pleasing ambiance, and it can depend heavily on the application and its unique architecture, including whether the application uses single Scenes, Multi-Scene editing, or additive loading. The following three sections describe the main differences:
While advice for lighting Scenes in Unity according to the above topics may be short, they are essential for proper workflow. For details, please refer to the sections linked above. Use the following recommendations from the beginning of a Project to help you use multiple Scenes correctly and achieve a smooth lighting workflow:
Enable Auto Generate only with single Scenes.
Do not mix Scenes with Auto Generate enabled and Scenes that have Auto Generate disabled.
Whether using Multi-Scene editing or additive loading, ensure that all Scenes used together have identical Lighting Settings, with a focus on Global Settings.
If you are interested in making great visuals in Unity please also read the Making believable visuals in Unity best practice guide.