Jagged edges for one reason. Whether cutting the pieces on a table saw, using a slitter, shears, etc., each piece will have edges that are not straight/uniform.Why not cut the laminate into pieces that are easy to manage? Use something consistent in width like a paint stick or similar to set all of your gaps when placing the pieces.
Best method I have found for this type of effect is to apply the laminate over the substrate with contact cement as normal, then using a straight cutting router bit and guides, cut the desired gaps. Produces the straightest, least chipped edges IMHO.