Q. Why do we repeat the Amidah? Surely it is enough to say it once?
A. The Amidah is the central prayer of every service.
Its opening and closing sections are standard; the intermediate b’rachot vary according to whether it is a weekday, Shabbat or festival.
It is always said silently by the individual, but if a minyan is present it is repeated by the officiant (except at Ma’ariv, which was not originally obligatory).
Explanations of the repetition include:
1. The silent Amidah is the private prayer of the individual; the repetition is the community’s prayer.
2. An individual may lack fluency in prayer or Hebrew, or both. The repetition is l’hotzi et mi sh’eino baki – “to fulfill the obligation for a person who is not adept.”