Although this was part of his Rosh Hashanah recordings, it is also used on YomTov in KAJ... Here is the bigger story as a friend of mine wrote me (CG): " The role of that tune is complex. It’s generally accepted to be sung by Tal and Geshem, plus Yom Kippur Mincha and Neila. Some Baalei tefilla have sung it at other tefillos of Yomim Noroim but none of the authoritative recordings have it there as far as I’m aware (there’s also a variation to the tune for the first words) It seems it used to be sung at every Yom Tov chazoras hashatz that had Kerovos, but that’s no longer practiced."