did this in a bout 90 mins. I simply painted over a previous painting of mine (see painting here). Painting on existing plates is definitely easier than painting from scratch because with an existing plate before you, you don't need to figure out what the environment will look like. You just need to rearrange stuff.
I added the black and white version so you can get a better grasp of the level of contrast in this painting; for we all know that value is one of the most important elements of art.