At Stanford, the metadata records are natively authored in ESRI ArcCatalog and then transformed into ISO 19139. The ISO 19139 records are then transformed to MODS for the library catalog and GeoBlacklight for the GeoBlacklight catalog.
Stanford University Metadata Workflow
Take, for example, the metadata for this layer. It has the ISO 19139 version of the metadata, along with the Feature Catalog (in ISO 19110). We also have the transformation into MODS and to GeoBlacklight, as well as a preview image. In some cases, you may even have an HTML version of the metadata for someone to read.
For scripts and other tools to automate or validate metadata workflows, see Scripts and Tools.