In the Slavic Typicon the Polyeleos is prescribed on Sundays from Sept 22nd to Dec 19th, Sundays from Jan 15th to Cheesefare Sunday, and any Sunday on which a Polyeleos rank Feast falls. On Prodigal Son, Meatfare, and Cheesfare Sundays Psalm 136 is added. On all other Sundays Psalm 118 is presrcibed. However, I think it is common parochial practice to use the Polyeleos every Sunday.
Fr. Deacon Lance