Unlike the novelist who is trying to paint pictures with words, leaving much to the reader’s imagination, your intention in administration, business or management is to convey information without decoration: to express your thoughts as clearly and simply as you can.
In a dictionary each word is first explained and then used in appropriate contexts to make its several meanings clear. This is necessary because words do not stand alone: each one gives meaning to and takes meaning from the sentence, so that there is more to the whole than might be expected from its parts. The words in a sentence should tie one another down so that the sentence as a whole has only one meaning.
The use of a word twice in a sentence, or several times in a paragraph, or many times on one page, may interrupt the smooth flow of language. This is why experienced writers try to avoid such undue repetition. But so-called elegant variation can be overdone. For example, in one paragraph on a sports page of a newspaper a team may be referred to by the club’s official name, by the colour of the team’s shirts, and by the name of the club’s ground. A reader has to be familiar with all these names to understand the message.
In business communications the right word should not be replaced by a less apt word for the sake of elegant variation. Instead, be consistent, always refer to a spade as a spade. You may also repeat a word to emphasise a point. For example, in the last paragraph the word by was used three times in one sentence - to draw attention to each of the items in a list - although only the first by was actually needed to make sense.