How I have setup my default import pipeline for Unity. These are my preferred values for Models, Textures, and Audio.
Unity's AssetPostprocessor lets you hook into the import pipeline and run scripts prior or after importing assets.
In a production pipeline AssetPostprocessors should always be placed in pre-built dll's in the project instead of in scripts. AssetPostprocessors change the output of imported assets, thus a compile error in one of the scripts will lead to assets being imported differently. This can be a severe issue when working in a production pipeline. By using dll's for AssetPostprocessors you ensure that they can always be executed even if the scripts have compile errors.
Unity guide on creating dll's: https://docs.unity3d.com/Manual/UsingDLL.html