As a post production mixer working in Film / TV and Radio - one of the most needed and often discussed features among my fellow engineers is a toggle feature that allows playlists to follow edits.
This essentially would allow all playlists below the main track to follow the edits of the main track.
Main uses for this are: re-conforming whole sessions in post to picture i.e. moving an entire mix by a few seconds or frames OR cutting a few seconds in shuffle mode to retain proper run time.
This feature would be hugely helpful when editing ALL tracks in shuffle mode while working on radio and podcasts to ensure all playlists follow along with the edits from right to left.