In light of this answer, why do we say V'imru amen and V'nomar amen at various points in bentching and davening when saying that passage alone? (eg. bentching by yourself, or oseh shalom at the end of ...
Ashk'nazi prayer books generally include the line ברוך הוא וברוך שמו after the zimun (invitation to say birkas hamazon and before the actual birkas hamazon. It generally (in my experience) is ...