The Book Was Better -- Or Was It?

Reading a novel before watching its TV/film adaption(s) is the correct order of doing things. Going the other way around I always find it challenging to picture my own visuals of a book's world and characters: seeing first someone else's vision of it and then replacing it is difficult. It's like most of the author's work had already been done and experiencing the story again via reading feels otiose. Comparing my own, already existing mental images to an adaption is more worthwhile.