Very true. However usually errors are small 1-2mm over 5000mm of roll lenght. The nasty part is that the errors are not consistent or repeatable to take them into account and compensate. Of course it depends on machine also, but most of the errors are some times there because over a 5m lenght of roll printed the mechanics inside heat up and the roll will travel more on a dilated feeding roll. Usually errors are in the long dimension, the left-right travel of the print head is usually very accurate.