The Harvard Business Review had a commentary on why winners keep winning. The gist of it is that a good win gives you access to things that make the next one easier. These can be broken up into a few groups

• It feels good to win: your mood’s better, you better mood causes you to interact with people more, and you’re less defensive so you evaluate what you can do better more critically
• You’re left alone to do better: when you’re winning, you get less interruptions to do the next thing. This is from yourself with negative self-talk, and then peers and bosses who intervene at moments of doubt.