It would probably my the jew very weak and sick. And if you were Jewish or had any Jewish blood in you? It would do the same to you, either that you would have this sense of knowing? And not to go there or even try it
Yes, it will undoubtedly lead to negative consequences and eventually destroy their soul if you do FRTR every day against a particular Jew.
In my experience, when you do FRTR against a particular Jew, the result is just instantaneous, you see how the Jew weakens very much on the same day and cannot harm you!
It is possible that the result of FRTR also depends on your strength, but no matter how strong you are, the ritual will work!