EDIT: huh, I opened a couple manga I had nearby and my original post was dead wrong
This isn't true in Japanese which is what limteary was asking about.
The primary exception is where the context of the writing itself implies a direction, e.g. text on the passenger side of a bus, or on a directional sign pointing to the left, may be written right-to-left so that the text "flows" in the same direction as its container. This would never be used for a longer text, though.