My voices didn't disappear, they just became more faint (and angrier). I was on the drugs for uhm . . four or five years, I can't remember - they never worked for me.
I was really sedated though, so I didn't care if I was hearing voices. (I would hardly have cared or noticed if I was about to be hit by a bus, though, I was so sedated.)

But your mileage may vary, obviously. Everyone's does. It's so personal and uncertain, nobody can be sure if the drugs will help you or not (or if you'll want them) until you try them -- and you might have to try several. One public person (off the top of my head) who claims she was helped by her drugs is Elyn Sacks, author if The Centre Cannot Hold.