One of the most influential points in my graduate school was when I worked really really hard, and failed to get a result. My advisor gave me this piercing look that without words said firmly, "I'm not angry at you, I'm just disappointed". That woke me up and got me on the right path.
technical approaches, mostly, learning not to reinvent the wheel so much, transitioning more towards using well-established techniques in the lab instead of going for broke on a risky project. I think a lot of figuring yourself out is knowing how to properly assess risk (while not becoming risk averse to the point of paralysis), hedge against failure, grab the low hanging fruit, and communicate the above to others.
+1, this is the kind of thing that changes the way you think when you find out.
Sometimes you don't need to be the genious inventing every single part of something to build something great, but we emotionally think we need to, because we often look up to people that did that as it looks too damn hard and wonderful.
Although I learned a LOT in grad school (and in postdoc #1, and in postdoc #2), I will have to say that choice basically ruined any chance I have at getting a faculty position in academia. If you can't join 'em, beat 'em ==> I'm starting my own research institute.
