I wrote an article about SLC artist Karen Horne a while back. I asked her if she does value sketches or paintings prior to starting a new painting. She said no, but she never starts until she can visualize the end result. Hmmm...two of my favorite artists telling me the same thing! My process is in two camps. Sometimes I visualize (with or without studies/sketches), but other times I begin with little vision or intention and allow the painting to tell me what it wants to be.