Is it obligatory for one who doubts the number of circuits (ashwāt) of the Farewell Tawaf (Tawaf al-Ifadah) and Sa'y after performing them to repeat the Tawaf and Sa'y?

Doubt after completing an act of worship is not considered [valid] and does not necessitate anything. It may be from the whispers of Satan. Imam Al-Shafi'i differentiated between doubt during an act and doubt after an act. He did not mandate repeating the latter because it leads to hardship. The repetition of the tawaf and sa'i has no bearing on the validity of Hajj. One is rewarded for performing a voluntary tawaf, but it is not legislated to perform a voluntary sa'i.