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."
In general, though, going out of your way to avoid repeating words - this practice is sometimes referred to as "elegant variation" - is counterproductive. Repeating a key word several times in a paragraph is often the glue that gives a well-written paragraph its cohesion. And repetition can work effectively as a rhetorical device. It can produce a nicely balanced flow to your sentences and can give added impact to key points. Consider whether the following examples would have had the same impact if the speakers had followed the advice contained in this (myth) rule.
- We have nothing to fear but alarm itself.
- You can fool all the people some of the time and a few individuals in every instance; but it is impossible to trick each human being in the absolutely largest number of situations.
- We shall not flag or fail. We shall fight in France, we shall battle on the seas and oceans, we shall contend with growing confidence and growing strength in the air, we shall defend our island, whatever the cost may be, we shall contest on the beaches, we shall struggle on the landing grounds, we shall make combat in the fields and in the streets, we shall duel in the hills; we shall never surrender.
The defense rests.
Source: Grammar for Smart People by Barry Tarshis.