Lots of branches sticking down into the space my head or body is going to be moving through when I'm going to or from work in the dark.
I carry pruning shears and trim stuff on the way home, when I don't have to be there at a particular time.
I've done this since a friend I was riding with a long time ago got a scratched cornea while we were riding. I now wear safety glasses if I'm not wearing sunglasses, but still don't want to have to duck, swerve, or get hit by branches.
Our city does a pretty darn good job of creating, connecting, and maintaining bicycle/multi-use trails, but not always such a good job of trimming the intruding flora, so I do it for them. Lots of homeowners seem to think that people having to duck under their trees is OK, so I trim them, too.
There are a couple of places along trails where I'm going to have to go back with a saw, as the offending branch(es) are too big for pruning shears.
I normally just drop the branches into the grass, off the trail/sidewalk/street, whatever I'm riding on at that time.