Hi MarieLouise, I'm afraid I don't understand your question.

Do you mean you want each word to show up only once or twice for the entire course? For example, "dog" will appear only in Day 1 and it won't reappear in any of the succeeding days in your course?
In general, LR will show about 6 words from each "Category" (e.g., Common Animals, Action Words, Colors, etc.) each day. The next day, LR will remove one word from each category, and then add one new word (from the same categories). This "remove one word, add one new word" process repeats until all the words in those categories are used up, after which the following days will feature words from a new set of categories (e.g., Fruits, Parts of the Body, Shapes, etc.).