How many times was barad due seen in the book

after so many viewings of the movies, and to many not careful readings of the books, I assumed barad due was always visible as soon as Sam and frodo entered Mordor. reading through as much of the chapters as I could last night, it seems barad dur was always wrapped in cloud and shadow. and only briefly do the clouds disperse so that they can see the top of barad dur, where presumably sauron is and see a red light from his window. then the shadows envelope it again. is this really the only glimpse they have, or did I miss something?