I have noticed lots of people struggle with Xref CAD Linked files on Revit Servers.
This can be due to a number of things different folder location setups for each office, getting Consultant or Client required drawings, in which you need to link to your Revit model.
The easiest way for me to do this is by creating a new Revit Model called CADLinks or something similar.
Once this project is created Copy/Monitor Levels and Grids from your actual Project.
Then for floor, elevation, section views simply setup multiple views for each level for CAD Link as required then load them in, ensuring that the Links are in the correct positions with the Grids/Levels.
I normally make sure each link is then set to Foreground in the views. This will ensure that the CAD file overlays ontop of the floors or other model elements in the Project.
Once this is setup I activate worksharing and save the file to the Revit Server.
Then in my main Project file I load this file in onto it's own Workset and then for any views that require a Linked view for any reason you can just setup the View Settings with the Linked By View option and the correct CAD Linked view selected.
This way if other offices work on the Work in progress file there is no double of CAD Files, plus in your Master file there are no linked CAD files at all, which means no issues with CAD files being duplicated, or loaded into the distance.
Other issues I've encountered is bad CAD files or Objects in CAD files causing problems in project files, cleaning up the amount of links in your direct Project File.
This also speeds up reference loading since all the data for the linked views is stored in the Revit File Memory so it doesn't need to load 100's of references if your consultants have been using CAD or you are working with large civil datasets and drawings.