רמ"א באו"ח סוף סימן רצג ונוהגים לומר והוא רחום וברכו באריכות נועם כדי להוסיף מחול על הקודש (אור זרוע
- It is customary to say V'hu rachum & borchu in a pleasant drawn out way, in order to add from the Shabbos to weekday.
The שערי תשובה there cites Halachos Gedolos (end of hilchos tzitzis) that one should draw out the words ברוך ה' המבורך לעולם ועד at the outgoing of shabbos, so that he should be saved from harm that week. The ברכי יוסף writes that he has seen written by the pure holy hand of R' chaim vital in the name of Rabeinu Hai Gaon Zl it a tried kabala that there is Hatzlacha (success) when one draws out and lengthens the saying of ברוך ה' המבורך לעולם ועד at the leave of Shabbos.
Question: Is this relevant when Motzei shabbos is also Yom-Tov (as on the upcoming Shavuos)?
From the R'ma it would seem that drawing out (V'hu rachum &) borchu is an issue of adding from shabbos to weekday. So it would seem that if its Yom-tov it wouldn't be relevant. But maybe the part about ברוך ה' המבורך לעולם ועד from the Halachos Gedolos and R' Hai Gaon would be relevant even on Motzei Shabbos which is YT?