sentence1: At best, experience with different combinations of waist sizes and leg lengths for a given design allows a scheduler to aggregate the units to be made into groups of large and small sizes, which means marker-makers can achieve efficiencies near 90 percent for casual pants.
sentence2: Marker-makers can only achieve efficiencies of 80 percent if they do not aggregate the units to be made into groups of large and small sizes and false is not true .