What have we learned? Now is a good time to reflect and reiterate (a) the market can never be timed, (b) declines of this size—if not of this speed—are as common as dirt, (c) you can never know how market crises will end, but you can be sure they will end, (d) equities/markets remain the only way most of us are ever going to achieve our goals, and (e) optimism remains the only realism.
In a way these past 5 months has been the whole movie. Normally the movie of such events last much longer. Again, a reminder that these type events although each a bit different have been happening an average of every five years since World War II.
The lesson is that for long-term, goal-focused investors highest-probability strategy is therefore simply to just ride them out.