Heres a useful question:

You are riding on the street, with traffic, and someone passes you, or you approach someone from behind. They are going at a decent pace, they are not slowing you down and you don't really want to pass them for one reason or another. Where do you position yourself?

I usually place myself about 20 feet behind the person, slightly offset to the left so that I'm less likely to crash into them should they suddenly stop. I find this appropriate for most people, and sdjust given the situation, but what do other people do? What is 'standard' if there is such a thing?