Question:
Why is there no mention of geulah before the amidah of Mincha and Mussaf?
Answer:
The idea of “smichas geula l’tefilla” is that we should say the geula, which is recited during kriyas shema and its brachos, adjacent to our davening shemona esrei. Since we say shema only once during the daytime and once during the nighttime, this applies only to shacharis and maariv.
Best wishes
Sources:
See Otzar Iyunim in the Mesivta Edition Brachos, vol. 1, Ma’areches 2.