I've always used a signal processing analogy for management communication. "Managers are lossy, high trasport-delay, filters." Any time a manager is between two people trying to transer information, there will be delay, and there will be information dropped.

Now, sometimes, that is a huge benefit. Not everyone can know everything in any organization of reasonable size, so there is benefit to having someone summarize information from other areas that I need to be aware of, and communicate only the bits that are relevant to me. OTOH, there are times when the best way to accomplish a particular mission is to get the manager out of the communication path so that the people with the expertise can communicate directly, at full speed and full fidelity, and deliver a solution.

So to me the litmus test for a manager is: "Am I adding value by filtering this information?" If no, then get out of the signal path.