If you look at the shot string like an MRI you have The pattern density at each layer or slice. The longer the shot string the thinner the pattern at each slice, or a stack of pancakes. If you have the sting over 10 pancakes instead of 1 if you divided the number of pellets by 10 each would have 1/10 the pellets of 1. Of course the pattern distribution is not equal between each pancake or MRI slice, each of those patterns will be less effective than 1. Brister used the trailer targets to show this by showing the length of the shot string.
