Picture below shown layout model for 6 cavity product, star layout used to connecting 3 cavity, then connected again with straight line. distance between one cavity to another is same
becouse flow at nearest sprue is faster than other, although the distance from the branch to gate is same, the flow of plastic will not good, nearest sprue will fill first and not same with another.
Improved runner layout
so we need another layout, below is improved runner layout for 6 product cavity, although is not the best, but it's more improved than first. but disadvantage of this runner layout is consume more material.