For me, high enough is 600mg, 3x/day for a total of 1800mg. I've taken anywhere between 900-2700/day, and on the lower end it didn't do much. I've seen docs try to put people on 300-900/day, and I'm not surprised when some report not much effects with regards to anxiety.

For what it's worth, I'm on it for a neuropathic problem and the anxiolytic effect is just a bonus for me. I hardly ever use the Klonopin script I have. I'm diagnosed with GAD, along with the BP and took Klonopin for years for it. Not anymore.