I use it in two different situations. I use it when brushing my teeth will bother my husband if he is sleeping. I also use it when I floss, but I only floss about 3 times a week probably.
The logic behind using it when I don’t brush is killing some germs before going to bed is better than nothing at all. Usually, I do brush my teeth, but if not, and I go to bed later than my husband, the brushing will wake him. A friend of mine is very prone to cavities, and she rarely brushes her teeth before bed. She started rinsing with mouthwash and her dentist says he sees a big difference. She didn’t get cavities for a few years, then I lost touch with her. No way to prove it was related, but it makes sense.
Regarding mouthwash when flossing—my ritual is brush, floss, then mouthwash. It just feels right. I don’t have any real particular logic behind it.
I used to like a clear mouthwash, I think it was made by Crest. I can’t find it anymore so I bounce around and use various different ones. I don’t love any of them.