Eh, kind of hard to really pare it all down. I guess here is just a brief hit list of things:
1) Evidence based/scientific stuff builds a necessary base for forming opinions/protocols/hypotheses but just because something is or isn't seen in the literature doesn't make it wrong (or right). I'm not sure if I was very hard up on this one way or another, but maybe this is more of what I've learned in medicine vs. training lately. This was a funny read too on the topic. In general, scientific rationale + personal experience= evidence based behavioral practices.
2) While many people are right, they are- at the same time, wrong. It's easy to point out where someone is wrong (including myself), but we must consider the audience, assumptions, and limited application that the author intended before jumping all over them. Common things relating to this matter include protein intake (people arguing for more or less), over training, high bar vs low bar, etc. To be clear, I think high protein intakes are good, over training isn't a big deal as long as your programming is intelligently planned that way, and low bar is a better main squat variant than high bar for any application involving a person who can LBBS without pain.
3) The mental approach to nutrition is >>>>>>>>>>>>>>>>>>>>>>>>>>> everything else.
4) The mental approach to training is more important than I previously gave it credit for.
5) Most people are more untrained, eat a worse diet (wrong macros, wrong cals, wrong food sources, or all of the above), and don't sleep enough than I previously though. There's no mystery to the outcomes here.
6) My own training experience is not typical (thanks Tom Campitelli for pointing this out).
7) Everything in life has a threshold, everything.
Other than that, nothing major has changed....just learning something new everyday.