I ride in the dark to get home from work (at least until daylight savings time changes) and my commute includes boh freeway and mountain roads.
On mtn roads, I slow down to be sure I’m giving myself a bit more room in case there’s a tree or some debris in my path. I also tend to ride a bit toward the center of the road as this gives me a bit more room to avoid the rocks and mud that tend to wash onto the right edge of my lane. I’m careful not to cross into the opposite lane, but have plenty of warning of oncoming traffic as I see their headlights shining off the trees ahead. My biggest concern is deer, though there seems to be more of those crossing the road around twilight than I do when it’s completely dark.
On the freeway where it may be particularly dark, I avoid being the first vehicle in a pack and instead choose to follow a bit behind a car. That gives me a bit of warning as they are likely to brake or swerve to miss large debris up ahead. I’m especially careful right after a 3-day holiday weekend as area roads are littered with a surprising number of kids bicycles, ice chests, beach chairs and other crap that has fallen off RVs and out of pickups.
I also use the Halo band and use to have it slip onto my neck every time I rode over 70 mph. I talked to the manufacturer and he actually said that it was a safety feature designed to make riders less visible to LEOs when you’re blasting down the road at illegal speeds. Sounds like a lame excuse to me.
But I found soaking the band for an hour or so in fresh water can put a bit more elasticity into it. Then I use a couple small loops of masking tape at each quarter to tack it to my helmet. It’s stayed on for a year since doing that.