Indexing for shared external local directory happens repeatedly, once for each user

[gbygrave]

I have a common media (music/films/books etc.) library that I make available via an external local directory to all users (It's read-only, by the by). I notice when carrying out an occ fulltextsearch:index that this library (largish - about 6tb) gets repeatedly indexed each time a users private files are indexed. Seems suboptimal. Is there a way to have such common shared content indexed just the once?

Running Nextcloud Hub 6 (27.1.5) and Full text search - Files 27.0.1.