Some years ago, a discount department store ran an ad in which two similarly dressed persons appeared. The announcer—in a loud, annoying voice—called out article after article: a dress shirt from a high-priced department store compared to a similar shirt from the discount store. “It’s the same thing.” After each item—the slacks, the tie, the shoes—he repeated in the increasingly obnoxious tone, “It’s the same thing.”
Repetition is a great learning device and a useful literary tool, when used judiciously. Redundancy, on the other hand, is essential in situations where a backup system prevents complete failure, but it should be avoided in your writing.