Does the X-Clamp Fix work?

I had the RROD and performed the x-clamp fix. I did mine with a nylon washer on each side of the motherboard and then a machine screw through the heat sinks, I didn't do all the drilling in the aluminum case. Mine has been working for at least 2 months now, with an average of 1-2 hours each day. My question is for those who have done this, how long has this worked for you? I was told this is a permanent fix, so just wondering if what I hear is true.