I'd say i'm within 5 degrees or so. My seating position will be inline with the front of a 40 inch opening that leads to another room. If i placed the surround at the front edge of the opening then it would be a good 12 inches forward of my listening position. Place it at the back edge and it's 35-40 degrees behind.

that positions 1 of the tweeters to fire directly at the listening position and the other into the back wall.