12 years for me
Worked up to 20 mgs of klonapin a day
I never took/take anything regularly, but once on a 3 day sleepless vegas trip, someone gave me half a klonopin. In like 10 seconds, my mind just stopped buzzing and I was just completely in the present, but thinking about nothing in the background.
It was fucking great, but also spooked me as to how fast and powerful it was, so I never tried it again.