In my line of work, I have to make presentations on a weekly and sometimes daily basis. Sometimes my presentations are not well received and sometimes they are. No matter the reception, I do the same thing at the conclusion each time. I head to my car and I immediately take stock of what just occurred, what did I do right, what did I do wrong? What could I have done differently? Self assessment is important during times of failure but what most people don't realize is that it's equally important during times of success -perhaps more important.Do you move on and forget about it, do you learn and change from it, etc.
This depends on the situation. Sometimes things/people fail for a reason. If you take a serious look at the reason for the failure you can either modify your approach or come to the conclusion that it failed because it is irrevocably flawed.