I average 20 seconds with ZZ, I think I know the difference. You don't do a cross in ZZ. The blocks in ZZ are blockbuilt because you don't restrict your solves by dividing them up into pairs like in CFOP.No you're thinking of roux. ZZ is a method where you orient all the edges before doing the cross. It allows you to do f2l using only L, U, and R sides and gives you a pre-completed top side cross. I used to like it because it also got rid of y-axis cube rotations (which are the slowest by far) during intuitive steps, and because it lets me get away with not knowing full OLL.