It never worked for me.
I had a bunch on my feet (7 on one foot, and anywhere from 9-15 at a time on the other. It was nasty.) and we tried everything to get rid of them over the course of a few years. We tried duct tape, several different OTC medications and ointments, even having the doctor freeze them off. They just kept growing back! (They were plantar warts.)
What finally got rid of them, after I had given up on it and resigned myself to a lifetime of warty toes, was garlic. Turns out it's a great natural remedy for warts! I did it on accident too... I went on a kick where I was eating a LOT of garlic dip (which would have equalled about 1/2 to a full clove of garlic a day...) within two weeks, I noticed that my warts were completely gone. It has been 8 years since then, and still no return. :)