For LPA I've always done 1 min on and 5 off, that seems to be the standard that most people go by and I've never tried anything else. My HPA cloner doesn't use typical HPA cycle times, I use more of a cycle that you'd wanna use for LPA, the reason for this is to keep the stems of the clones wet so that they'll actually root, I have however ran HPA for reguar grows and my timing was usually around 1 second on and 3-5 min off, you have to play with it to get it just right for the setup that you build, timing for HPA is 100% dependent on the root chamber design, sprayer design, pressure, solenoids, ect.