It depends on a lot of things for me. I always rip out the mistake and press immediately after a stern talking to myself for being an idiot and telling myself I need to be more careful. I want the tear out process over so I don't have to face it if I decide to walk away. I then decide if I can start again or if I need a break. Sometimes I just make a cup of tea, or something and go right back to it. (With the tea across the room so I don't create a bigger mistake by a spill.) If I decide the mistake is because I am rushing...I tend to make impossible goals for what I want to accomplish during a set time, I stop. I know I will go back to the rush and mistakes will abound!