Experience
Some say that experience is the best teacher. And baring learning styles, there's a lot of truth to that saying. And not just learning by doing. Learning from your mistakes. And even better than that, learning from other's mistakes.
But the real key to experiential learning is not the doing of the thing, it's the reflection afterward. In school you might call it the lab report or case study, and at work we call them tech sharing or incident reports, but regardless of the name, the goal is to identify the parts that made a difference and why so that they can be incorporated into our internal understanding of the world. We can then use that understanding to inform future decisions.
Because if you don't reflect on what happened and why, you're not really learning, you're just setting up a conditioned response. The next time something happens that is similar enough to trigger your filter you'll make the same response. Of course the situation is not the same, It might be close, but if nothing else time has passed. And if the trigger is close enough the same response will probably work. Thus reinforcing your "learning"
Which brings us to the story of the 5 monkeys. You know, the one with the ladder to a banana on a string. If you don't know it, the short version is that a group of monkeys learn that climbing the ladder brings on group punishment. Once they've all really learned that the monkeys are slowly replaced. Each new monkey learns that climbing the ladder gets them punished by the other monkeys. Eventually non of the monkeys have ever experienced the punishment, but they continue to train new monkeys in the group to not climb the ladder. While the story is mostly apocryphal, there's still a lesson to be learned.
Learn from your experiences, but reflect upon them and understand what the learnings really are. As we go forward come to inflection points where a small change can have a large impact. We're approaching such a point, so let's make sure that our decisions now are based on the learnings from our experiences, not just "that's the way we've always done it here."