run of the mill pre-pregs are heavier then a careful wet layup but the pre-pregs allow for a less skilled labor force. When reducing the amount of material, the orientation and wetout become super important. With prepregs the resin/matrix ratios are more predictable and variations in skill are all but eliminated, The shape of the pieces is also more fixes as the resin holds the fibers in place and there is much less distortion. Pre preg is also much faster to construct. If sailplanes were to be wet layup the costs would be in the range of 15-20% more.