Consortiums involve group effort--which is good; however, it also demands an ability to work together and come to an agreement on practice. It also helps to have someone overseeing/coordinating effort.
When it comes to authority control, there usually needs to be someone responsible for loading regular additions and updates--as well as deletes. Libraries that use a vendor to asist with the automated checking for new authority records, updated or deleted records find that it saves alot of staff time for the bulk of the work but there has to be a primary contact person to work with the vendor so records are loaded regularly and properly as well as to address any needs that come up. For libraries that still do everything manually, the issue is making sure all participants agree on what is required by the local system. In every setting (Library and otherwise) the comments I've heard is that it accuracy and consistency really does improve retrieval. So whether you are a consortium or individual library, some form of authority control is needed.