As Bismark said - "The wise man learns from the mistakes of others."
So, don't learn from your own mistakes, try and get it right first time.
Here are my own little rules to help you from learning from your own mistakes.
You should do this because you know that once you have delivered everything they want - even if it looks like a bag of shite and acts like a bag of shite. If it was a bag of shite that they really really wanted in the first place then it will be your bag of shite that makes them happy and brings home the bacon.