Where is the challenge?
When I test out of skills in German I receive the same question over and over.They give me a sentence and ask me to translate it. For the next question immediately following it, they ask the exact same sentence but for the multiple choice section. Then they give me the translation of the exact same sentence and ask me to write it in English which is still fresh in my mind from all the previous questions. This repeats until the end of the test. This makes it far too easy to advance. Is this by design?
I realize that repetition is the mother of skill and I don't mind sentences being repeated throughout the program, but when you are testing out of a skill, as opposed to learning a new skill, you are showing that you have already mastered it and using identical sentences during a testing session is too easy. It is simpler for me to test out of a skill than to do the regular exercises due to the fact that I sometimes get only one particular sentence that is repeated well beyond the four times required to test all main skills in a skill test session. There about 20 questions in a skill test session. They shouldn't be all the same even if you are trying to cover all main skills of listening, reading, writing, and speaking.
I totally agree with Cyclone. Repeating is fine, but when testing, there should be no repetition, but rather one example of each possibility. However, I'm not sure that commenting it here is the best way to give feedback.
Repetition is key to learning a foreign language. That's why the same phrases are used over and over again. Note also that the repetitions are often related to a different skill, out of the four main skills--reading, writing, listening or speaking. Having said that, I've noticed that Duolingo is still a work in progress. They keep adding new exercises and skills as they go along.