How far? Here's one example of Coyotes not following the rules at all.
Two years ago, my calling partner and I set up at the end of a 200 yard by 75 yard field with the wind in our faces. I snuck out and set the E caller up about 40 yards from the end of the field. My buddy took one corner and I took the other. To get down wind of us the coyote would have to use small strips of woods on either side of the field. Well, after about 20 miunutes, we had no takers, but when I went to pick up the caller, there were fresh coyote tracks that came right down the middle of the field to the caller and then turned right around and went back the way they came. Snow has a way of showing you just how bad you have been had.
In my experiance though, the coyotes here in NH will circle only as far as they have to. If they have good cover, they may only get 20 or 30 yards down wind of you, which is why shotguns are so effective in this type of situation. If we hunt fields,they will use the wood lots that separate those fileds to get to the other end and often just stand there looking until they decide to make a move. Usually.
If you ever get the chance to call in snow, you can learn a lot by just taking a walk after a stand. Often you will find you were busted by an animal you never saw.