First, I'll say that most people don't spend enough time thinking. If they did even a little more of it, especially before opening their mouths, life would sure be different.
Beyond that, my conclusion is that the only time you think too much is at the point where it prevents action. Whatever you want to achieve, if you spend time thinking about it, but don't actually do it, there's a problem. Which is why I'm keeping this blog entry short, to go and write today's script pages.
Let me know what you think.