Sometimes a project is broken up into a series of separate files linked into the main central file.
This may be done to separate out particular information - like Context, Site, adjoining buildings.
It should also be done if there are more than 6 to 8 people working in a single Revit file. Typically existing worksets are separated out as linked files - e.g. facade, fitout, structure.
Linked files are usually central files themselves (i.e. worksets are enabled so multiple people can work at the same time).
Whether central files or not management of these files should follow the same protocols as the main central file.
Refer to PROTOCOLS>MODEL MANAGEMENT>MAIN CENTRAL FILE.
If a particular linked file is not worked on very often the procedure can be changed to it being compacted after any changes are made rather than on a regular basis.