8
It would seem that original Minhag Ashkenaz was to use ta'am elyon only on Shavu'ot, but on shabbat parashat yitro and shabbat parashat va'etchanan to use ta'am tachton. This can be seen in the commentary of Hizkuni to Shemot 20:14, and is also the practice prescribed by Masat Binyamin, quoted in...