How much do the skies differ in your landscapes? Do you work on some paintings with a snarl on your face and others with a grin? Do you have a standard cloud pattern that you use on all your work?
For homework, make a painting with two different skies. You may need to make it one that has nothing but sky above the horizon, so you can just set the second sky on top of the first for the photo. Then send both images to your monitor.