There are languages with regular stress, for example in Polish stress almost always falls on second-to-last syllable. So when you hear stress you know the word

There are languages with regular stress, for example in Polish stress almost always falls on second-to-last syllable. So when you hear stress you know the word is about to end and the next word will soon begin. In practice it's not 100% true, there are regional differences (in Kraków people stress the first syllable instead), so it's not the only factor.