Layer files are good, however as soon as they are loaded into ArcMap the link to the LYR file is lost. This means that for corporate layers if we change the source or styling, all the old MXDs will have the original data/styling.
So, a solution. A modification to the LRY file for it to contain a GUID. And an option on the layer properties to retain/restore layer to original state, plus storing the lry file location in the MXD.
When a layer is loaded into a MXD it stores the LYR location and GUID.
When that MXD is opened again ArcMap checks the LYR file stored and compares GUIDs. If there is a difference it loads the new properties of that layer file. If not it continues.
If a user modifies the proeprties in any way the link is "broken" and the start up checks are by-passed. However there shou;d be a "restore to default lyr properies" button to remake the link.
Implementing this idea will help all of us with large corporate networks to ensure all our users have the right data, displayed in the corporate way.