Generally, if the scope or mast is not in use then it is lowered. It basically depends on what is happening when a particular image is taken. There are many shots of boats tied up at the dock with the scopes down. I have several of Wahoo departing for patrol and the scopes are down but the radar mast is extended -- which makes sense.
I think modelers tend to show them extended because they make the model more interesting visually. And if it is an r/c boat, and don't have a method to raise them while underway, then you would want to leave them up so you can run at periscope depth.