New answers tagged chagim-holidays
Well there's this Rabbi Adir HaKohen who brings a small siman (from Rosh HaShanah daf 14b) for why the focus is the evening. In addition, here's a collection of halachos for Tu BiShvat, where the rabbi brings one source for day (Even Yisrael) and two for night (Yafe LaLev and Moed Lekol Chai). Do not know these sources well enough, sorry :)
Bnai Yissaschar is based on the months and thoroughly goes through each Yom Tov.
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