In the notes about the Hunt and Kill preset, it says that pathogens mutate and therefore we need to change the frequency slightly each time we apply it in order to kill them.
With GeneratorX (GX) Hunt and Kill mode you can perform faster biofeedback (BFB) scans and automatically run those BFB scan results on the other GX generator using Remote or Contact mode. So it the pathogens are ducking and weaving to avoid destruction, GX is going to nail them assuming that they can't change faster than the Hunt and Kill cycle takes to complete.
Prior to GX users had the option to use frequency and amplitude wobble as well as different waveforms to try and knock out a pathogen. So if you look back through previous user success reports you will find a variety of methods were employed to nail a pathogen besides using the same frequency repetively.
For more details, please check the link: