The implication of the Rambam (Hil. Berakhot 5:3) and the Rosh (7:27; although note the reading of the Bach) is that the mechanism of zimun entails every member fulfilling their obligation through the birkat hamazon of the leader. The Shulchan Arukh (O.C. 183), having noted in Beit Yosef that it is considered too difficult for the members to listen to every word from the leader, writes that it is proper for each member to recite the words silently with the leader. The Taz (193:2) notes that this is a concession, and an appropriate one, to modern weakness, despite the superiority of the method of each member listening to the birkat hamazon of the leader. The Resp. Avnei Ya’akov (31:1) suggests that the reason the ideal method is not even encouraged in contemporary settings is that the leader has no intent to discharge all the listeners in that manner and they would thus rely on him unjustifiably.

The Rama recommends that for each berakhah, the individuals speed up toward the end to finish before the leader, to allow them to answer amen. The implication of the Resp. Panim Me’irot (I, 57) is that this is a type of compromise; by listening to the ends of the berakhot from the leader, some form of the ideal method is utilized, while the need to listen to every word is alleviated. (See Magen Giborim 183:2; Resp. Tzitz Eliezer XVI, 1:6; Resp. Yabbia Omer, I, 11).

In explanation of the ideal method, many acharonim (such as Rav Soloveitchik [see Shiurim L’Zecher Abba Mari, II, pp. 81-104; Eretz HaTzvi, 5; Am Mordechai, 26]; Bad Kodesh, IV, 1; Resp. Beit Avi, II, 6) explain that it is not the commonly found “shomea k’oneh”; that is utilized in allowing the listeners to fulfill their obligation through the leader. Rather, the recommended format of zimun is that the entire group offer one joint birkat hamazon. Thus, the leader is articulating the prayer that is being offered by the group as a whole; the members all listen intently to his prayer in order to join in the group.