It is true that there should be a unique freq (or maybe two) that kills a pathogen. However, some other creatures like parasites (taeniae, worms) lay eggs so more freqs are needed to kill the eggs and larvae.
In any case, some "support" freqs are needed, like antibiotics, detox, liver and kidney support, pain relief, etc. It is true that some of them are redundant but don't hurt anything.
Attached is a pdf with a list of most common freqs used and with explanation of what each freq is for.
For more details, please check the link: