Repetition is a tricky one. If you do it too much you are repetitive but if you get it just right it makes your ideas clearer and more memorable. You don't have to just repeat the same word, it can also be phrases or even full sentences! How many times did that big bad wolf stand outside a little pigs humble abode and huff and puff. Surely after the first time he would have realised that another technique, such as a bulldozer would have been more effective. Of course, the audience of the story would probably not have benefitted if the repetition had been replaced with instant demolition. He went to the first house knocked it down end of, time for bed. Ouch!
If you want to be more highbrow then think of any poetry you may know or if you are stuck then look at song lyrics. The whole of 'Happy Birthday' is on repeat you just insert the appropriate name and the message is crystal. In fact, the definition of chorus is a part of a song which is repeated after each verse. The repeats make the music easier to grasp, understand and above all remember. For the same reason, this is why repetition is so useful and effective in advertising. Fill in the blanks, 'have a break, have a .......'. !
For such a simple technique repetition is really, really effective. It is both a literary and a rhetorical device, so what's not to love!
Repetition is a simple word to embed the words and ideas.