When is comes to the choose of the hot runner cavities choose, mostly we take the effective of the production in the first issue. What is to say we made the hot runner to made as many as cavities as we can . And also we must take a careful consideration of the banlance of the runner which is the most improtant case when we desigm the hot runner cavities layout 

Hot runner cavities layout should be benfit both hot runner effiency and its runner banlance. Such as : when we arragent cavities with different shapes. we would be better put even number cavities together, so that the runner can be banlanced. And for odd number cavities, we should apply the special design in the hot runner to ensure the banlanced. Such design is that use different runner size in different running way. And for very tiny products, people generally want to cavity distance arrangement as close as they can , But minimum cavity distance is limited by the minimum distance between the nozzle size. so we should check the nozzle distance be fore we design the hot runner cavities layout 

Anole is a top quality hot runner system maker in china. Any interesed ,please contact me freely.