i can build the x-cross less than 12 moves about 5 to 10s but some people can do about less than 8 moves and it takes about 4s or less so what is the fastest way to build the x-cross
X-cross is meant to be used by Fridrich cubers in situations when a 2x2x2 block is faster to build than half a cross with an F2L pair filled. So in other words, use X-cross when you see a 2x2x1 block and attach an edge or something like that.