After you call a foul in the attacking area, you often have to manage the defensive wall. Besides making sure that the wall is at least 10 yards away from the free kick location, what else do you have to manage? On a contested game, there may be extracurricular incidents after you call a foul, away from the ball. This is why you should always keep as many players as possible in your view. You also want to keep your assistant referee in your view.
Below is a video example of how a referee could have done better with his wall management.