Midsummer and Midwinter have resonance. They have immense myffic whatsis. And I have leaned on that whatsis in the past, and will again. But what they do not have, so much, is texture. "This non-equatorial culture has a Midwinter Festival!" You don't say. Golly, just imagine. But if you say, yes, of course, Midwinter and Midsummer, harvest and planting, rhythms of life and all, but also, also, also the day when this nation cut loose from their neighbors to the west. Or the day when the founders landed on the barren bit of rock. Or the day when one subculture observes one thing while another is up to something completely different and the two of them are not entirely pleased with each other for doing it wrong and ruining the whole thing. Or the day when the decadent cityfolk drink and dance, but this is serious to the farmers! this is hard work!
And it's all being character again: you know something about my mother if I tell you she tends to observe Arbor Day whenever possible, as a suburban person in a non-agrarian culture. Similarly you will know something about Lord Wossname of Thatplace if you know that he does not give the servants the day off for the festival of fools and has lost two cooks over that point but will not yield, despite his sister's shouting on the subject. Do people know songs for Brewer's Thirdday, or is it a non-singing holiday? It's not about treatises. It's about what drops into the lines as you go.
It makes it nubbly. Sometimes you want things to flow past your fingertips without catching, but sometimes being able to feel and see the stitches is just what makes it interesting, and maybe a little beautiful. And also sometimes where your fingertips catch is where you've dropped a stitch, and you need to go in and repair it or rip out that row before you get any further, and that's all right, too, because it is worth doing right.