Oh yeah, It's nearly impossible for a painter to always be "right." In fact it is only through mistakes (and sometimes disasters) that I've ever learned anything worthwhile.
Sometimes I even stumble into same mistake multiple times - like sticking my finger into wet paint to see if it is dry and messing up something it took hours to paint...but I eventually learned that it takes Ivory Black much longer to dry than my other colors. Duh.
And for pete's sake, there are so many goofs that I make each time I pick up the brush that I often wonder if I am painting or merely "correcting." And truthfully, I wouldn't have it any other way. ;o)