Details are a vital part of the documentation process for building design and construction projects. CAD users who have used AutoCAD for years have typically developed a large detail library, or at least possess many details used on previous AutoCAD projects. Those details are valuable as a lot of time and knowledge has gone into developing them. It is important to be able to access those details for usage within Revit.
While there are various methods utilized for re-using AutoCAD details, not all of them are good solutions and some can add corruption to your Revit project file and create problems.
There are times when a door (or window, opening, or door/window assembly) gets placed into a wall that has another wall (or multiple walls) adjacent to it. Even though a door can be placed in only one wall, it is possible to create an opening in the adjacent wall(s) so that when the door is relocated or changes size, the opening in the other wall(s) change accordingly.
Autodesk has finally fixed a major wall cleanup issue between mirrored xreferenced drawings in AutoCAD Architecture!
Cleanup between overlapping walls in different xreferenced drawings was introduced several releases ago in AutoCAD Architecture (Architectural Desktop name at that time). As they continued to improve the feature, walls still had problems cleaning up properly when the xref was mirrored. If an existing xref was copied and mirrored, the mirrored version would have gaps in similar locations as the first instance of the xref. If an xref was brought in and mirrored (without being a copy of another xref), then the xref would not cleanup at all. Either way, walls in mirrored xrefs would not cleanup correctly with walls in other xrefs.