Going out of your way to avoid using a word you have already used a few words earlier was useful advice when you were writing school papers and one of your goals was to impress your English teachers with the size and range of your vocabulary. It is also a good principle to follow when it comes to certain types of words and expressions-phrases such as "on the other hand," "to make a long story short," "of course" - and, in particular, "like" and "you know."
