Some exclusions are made in a normal way. Even in my office, investigations are conducted confidentially, so if you look at requests that were sent to us, you'll see that we often have to redact, because our investigations are done confidentially.
However, I'm telling institutions and departments that, if they are able to provide information, they should do so. People will have a better understanding of the decisions and a greater confidence that the information they receive is reliable. They'll be able to understand the decisions and policies of a department.