Suppose you are writing a test paper. You do the best that you could. But after coming back and checking and rechecking your answers with more reliable sources you realise that you have made a thousand mistakes, and are, well and proper, screwed. Can you still expect to get good scores in that particular paper? No. Is it even remotely justifiable to hope so? No. The maximum you can hope to do is not commit those mistakes in the next paper. But as for now, this paper of yours is beyond help.
All our ventures are somewhat like that. Be it on a personal level or on the professional front. Once you make a mistake, the most prudent thing to do is to start afresh. Because, let’s face it, no matter how hard you try, it will never be the way it used to be. Things will be far from perfect. And what’s the point of life, if it’s not perfect.