My weekday riding, however many they are, are usually spent riding alone. It's not by choice, not cause I want to focus or anything, it's just that my riding buddies have work and other responsibilities that prevent them from riding on a weekday.
I ride with at least one person on weekends though. Riding alone is not very fun compared to riding with buddies. I'm all quiet, and not being able to shoot the shit after runs is really boring. But most of my riding time has been done alone.