"" Picasso said he was painting every day, "he told us.”I can say, I paint day after day." He once told me that he was counting over six thousand paintings. When asked how long it took to complete a painting, he replied: "Forty years and two hours." The experience, you see, had the biggest part. Other paintings, of course, were quick and others were not – he would turn them on the side and paint them again. At the end you can always tell the ones who have a lot of work put in them and a lot of detail.
Source: tovima.gr