Fisrt, I know that I will get a lot of flack from this but what I say is the truth and has nothing to do with whether or not I sell a zapper.
We tried this a a couple of years back and did not get good results. What we found is that for some parasites it is necessary to maintain the same frequency for the full seven minute minimum or they can recover.
This does not mean that it does not work well at all and it does not mean that it doesn't work for most parasites.
It just did not work for us so we do not offer a scanning zapper or a sweeping zapper.