It always takes time to get that wonderful idea that's in your head, out into paint.
Often a painting gets to a point where, I'm done with it, I've put in a lot of hours and it's looking really good - certainly salable… but I know it's not done yet. It doesn't fascinate me enough. It needs more time.
So I'll set it aside, let it simmer... days or months later, with new eyes, I know just what to do. Sometimes, it's just a stroke or two.