Art & Fear by David Bayles and Ted Orland has an eye-opening story about quantity and quality. It beautifully explains the difference between theorizing and taking action, worrying and "just getting it done" attitude, and the fundamental effects of the superior one. Here's the story:
At the start of the course, a ceramics class was divided into equally sized two groups: students that would concentrate on making as many pieces of pottery as they could, and students that would only make one piece - the most beautiful they could. At the end of the course the works would be graded - a student in the the quantity group would get an A if they produced 50 pounds of pottery, B if 40 pounds, and so on. In the quality group, the student's one piece they'd been working on all semester would be graded, but to get an A, it had to be absolutely perfect. At the end of the course, when the works were graded, the pieces of the highest quality were all produced by students in the quantity group.
You may be thinking, what the hell? As a quantity group student, you could get an A by just making the simplest and the heaviest vase identically over and over again until 50 pounds was reached!
But you know what would happen in the process? You would perfect the simplest and heaviest vase. It would become spotless, absolutely flawless, a masterpiece.
And that's the point. Some people worry so much about their one masterpiece they start to panic before they even get started. They analyze and overanalyze the theory of how to make one perfect piece. When they finally choose their design and method, there is either so little time left to produce it that they make mistakes, or they're so certain they're going to make one little error that they end up making that error.
What happened with the quantity group? They got grinding on the first day. They finished the first piece (probably awful), learned something in making it, started and finished the second piece (still awful, but not as much) in which they took advantage of what they had learned in making the first piece. This iterative, constantly improving process continues until the collection weighs 50 pounds - at which point the latest pieces are truly amazing, having been made with the cumulative knowhow from the other pieces.
So which group are you in? The one that overanalyzes and fails, or the one that takes action and improves their skills continuously?