We have a shared account to manage servers as well. However, the individuals still have individual accounts, and individual SSH keys. They log in as themselves, and `sudo -iu` into the shared user. This can be done without giving the user root (i.e., sudo supports only giving access to the shared account).

It's still not a great setup, because it makes auditing a nightmare. (Unfortunately, a particular software package we use essentially requires it due to its bad architecture.)