The conclusion of Maran the Shulchan Aruch (Rabbi Yosef Karo), based on the Biur Halachah and other decisors, is that if an interruption lasts long enough to finish reciting the entire text—whether it is the Recitation of Shema, Hallel, or a blessing—one must return to the beginning. However, this applies as follows: if the interruption was not due to an unavoidable circumstance (oness), one returns to the exact place where they stopped. But if the interruption was due to an oness—for example, if a person needed to use the restroom in the middle of Shema and remained there long enough to finish the entire text—according to Maran the Rema (Rabbi Moshe Isserles), he must return to the very beginning, whereas according to Maran the Shulchan Aruch, he returns only to the place where he left off. In practice, Ashkenazim also return to the beginning only for Torah-mandated obligations (D’Oraita), such as the Recitation of Shema and the Grace After Meals (Birkat HaMazon); however, they are also stringent regarding the blessings of Shema, since they are drawn after and associated with the Torah-mandated obligation of Shema itself (Biur Halachah).

Therefore, if melodies are being sung, one should keep moving forward until the end of the blessing, unless the melody is sung while simultaneously pronouncing the words, which is not considered an interruption at all. Similarly, a person who pauses to wait for the prayer leader (Shachatz) to conclude a blessing so they can answer “Amen” is not considered to have made an improper interruption.