I've been on a steady course of self-education since 2005. With some boglehead help, I simplified, and then expanded our total portfolio. However, I learned during this Great Recession that other strategies exist, and you don't have to ride things down 50%, and wait a few years to return to the previous high. Since we are accumulating, the lessons learned are different than for an early retiree. In fact, there are so many variables, such as when you started, etc., that some up control to an FA, or even a dogma.
I've seen a great deal of success applying momentum investing concepts to our retirement funds which receive new money every week. I follow moving averages on all of our funds, so that I have a very good idea of where things have been. I can't predict the future, but I have a plan for mitigating some of the downside.