Why in quran are so many surahs repeated over and over just curious?

Surahs (chapters) are not repeated, Ayahs (verses) are, for example surah Ar-Rahman does this by repeating the verse ''Which is it, of the favours of your Lord, that ye deny?'' after every favour it repeats this to place emphasis on these favours. I would also like to add that the Qu’ran was never meant to be a science book, it is a book of guidance such repetition and emphasis would make it more efficient in its cause. And Allah knows best.