I have no center vision because of a stroke. If I make a mistake I rip it out right away. If I make another, I rip it out again. The third time, I bundle everything up and walk away. It may be an hour or a day. But I feel that I am doing a horrible job and can't let it go. It is basically up to you how much you can put up with. I know I crocheted an afghan after I lost my sight and after I finished noticed a mistake in the 6th row. Needless to say my husband saw my arm going up and down while I was ripping out. I'm not perfect, but if I know there is an error, I can't let it go even if I know no one else will notice it.