When cycling alongside traffic, there's always the worry that drivers of motor vehicles won't see you. It's especially worrisome if it's dark, raining, or foggy (or any combination thereof). Add rush-hour traffic, and it's even more nerve-wracking. Not to mention road surfaces that are long overdue for repair.
Even though most of my riding is done away from traffic, I usually wear a reflective vest. Usually -- now and then I forget it! (I'm human, after all).
This morning when I rode, there were fog patches again; some of them very thick. Such conditions make me wish my headlight were 1000 lumens instead of 500. On second thought, backscatter from such a bright light might make it even harder to see. I won't know unless I try it.
As usual, there were people out there without lights. Don't they want to be seen?