Performing Tahajjud Salaah in pairs of 2 and 4
Q: We know that praying 8 rakaah in tahajud is sunnah but there is no limit on the number of rakaah.
My question is should we pray these 8 rakaah in pairs of 2 or 4 and if we want to pray in pairs of 4 for example 4+4 is 8 so should we recite another surah after fatiha in the third and fourth rakkah because we know that reciting a surah after fatiha in the third and fourth rakaah is wajib in sunnah e muakadah and ghair e muakadah.