I Swap & change mine all the time, at the mo its a woodland snow scene. At xmas I had a beautiful pic of cosy fireplace & tree all decorated. Sometimes I have a lovely blue sky with fluffy clouds soon I'll change to a nice spring scene.
Do you mean desktop picture or screen saver? They are different things. My desktop changes whenever the mood takes me, it is a slide-show of roses at the moment, I don't have screen saver enabled.