Railing security regulations often state a maximum distance between balusters. Suppose you want a simple railing, consisting solely of a top rail, a bottom rail and evenly placed vertical balusters. The distance between the balusters should always be equal to or smaller than the maximum distance stated in security regulations.
Suppose the maximum distance is 110mm.
Suppose the square balusters are 25x25mm.
In the Main pattern dialog box you would then only have one "Regular baluster" and set 135mm (=110+25) as the "Dist. from previous".
When setting justify to "Spread pattern to fit" you get evenly placed balusters, but depending on the length of a railing, the distance between balusters sometimes exceeds the maximum of 110mm, like for example 115mm in the example below.

Having a justification-option to "Shrink pattern to fit" would be extremely useful. You would get evenly placed balusters and the distance between them would always be 110mm or less, in other words always respecting safety regulations.