There's IIRC 3 or 4 people in their department, they administer the whole building (wifi, security cams, LDAP, etc.), not only the on-premises servers. From what I gathered, our internal systems usually go down due to lack of disk space or some bug in the software which requires merely a reboot, it's not rocket science. Another thing is that our IT department (for internal systems) and the SRE department (for client-facing systems) have 24/7 on-call duty so it's unlikely that no one will respond.