I haven't "come full-circle", but I've had a similar experience. I haven't read all of LessWrong Sequences, maybe not even half. Some old friends of mine got me into the meetup at a time when I was studying microeconomics, and started majoring in cognitive science. So, I was enthralled by discussion, and went around the Internet and life learning about related topics. Occasionally, I read Sequences essays I haven't read before, and I realize I get the gist halfway through reading it. That's my "yeah, I know about this...". It works for me epistemically. It might have helped that I tried to rationalize the existence of the Christian God as a child, up to the point of deism not specific to any religion, and finally to virtual atheism. I found by the time I encountered arguments for or against the existence of God in theology or philosophy in university, I wasn't phased by any of them because I'd generated all of them on my own before. That's another "yeah, I know about this" set of experiences, rather than a series of "Aha!'s" I expected. These mental exercises may have prepared me for future thinking on LessWrong. Sometimes I'm not as curious as I used to be, and I don't often automatically think of ways to optimize. Instrumentally, I don't believe I'm "on the right path" for fulfilling my own goals. However, that is confounded by other factors of my own life I'm not willing to discuss publicly. So, I'm unsure how instrumentally rational I may or may not be.

I don't have a link, but something like this was already mentioned on LW... when you have already mastered some kind of thinking, it seems "obvious", even if it seemed original and awesome when you were reading it for the first time. Although, this only proves that you have become more familiar with LW style of thinking. It does not automatically follow that "LW style of thinking" is "rationality". (Although I personally believe it is related.)