LIGHTROOM - Duplicate Collection Set heirarchy
Allow the duplication of a collection set AND it's constituent collections so you can rapidly re-create the structures you use for event photography. Put 2 options with it - copy hierarchy and to have the collections also include existing photos if desired, along with a text tag to make names catalog unique - pre or post appended. Or, a template structure to be used as a master to achieve the same result. It's a pain to set these up as is in LR CC.