All the shot on the plane of the target instantaneously would be the ideal. It can't be done. The target moves as the shot cloud passes. This results in a loss of effective pattern density for anything that has any relative motion to the axial direction of the shot. What shows as a hole on a stationary board would present to a moving target as a tilted cylinder in the cloud, and be essentially meaningless for predicting the chances of a target being hit or escaping.
For all but high deflection shots at long range, the % loss isn't that dramatic but for any moving target what you see on paper isn't what you get at the plane of the target.
