Much like the Zen ideologies, there is no end state to being a rational human being. You can't just stop at one point and say "That's it, I'm perfectly rational now, therefore..."

Instead, it's more of an ongoing process. The process of identifying your biases and reasoning about them is on-going. You will always have biases, the trick is to make the subconscious influence conscious. To come back to the Zen comparison - the more rational you become, the more you realize you're not rational at all.