The writer must be able to figure out how to limit the effects and still tell the story. Start with one matte shot of the castle, for instance, then go inside and let the rest of the scene play out on two sets. When you have it on the page and people read it, it makes sense to them. On the other hand, if you write the same scene to go inside the castle, out on the parapet walls, back inside through fourteen rooms and end out on the roof, you have just made that same scene four times more expensive, probably without adding a thing dramatically.