I have read reports of people who found draugr hanging around unusual above-ground locations, like right outside a city's gates, after the PC fast travels there. Not heard of any small detachments of them just marching down the road. Maybe they are new draugr recruits and didn't pass inpection and the drill instructor sent them out to do a forced march in full gear in broad daylight as punishment.

Most unusual "on the road" encounter I've had was riding back from somewhere towards Whiterun, had just crossed over one of the bridges there at the crossroads down by the meadery. Some guy walking along the road in front of me, also towards the city. As I pass I hear him say "Is somebody there?" or one of the other standard bad guy lines that you hear when one of them detects you and is about to go aggro. Next thing I know he's attacking, by the time I stop and get off the horse the guards on the road are all going after him. I think I turned around and got one swipe in with my own weapon before he went down. When I searched him he was a Bandit Marauder or Bandit Chief, I can't remember which. Just walking down the road being a bandit with all those guards around and none of his crew to back him up. Not a very bright bandit, maybe that's why they all deserted him.