It is important for the quality of knowledge obtained by means of SuperMemo, that repetitions are conscious and semantic, i.e. they do not just reproduce the answers automatically, without truly grasping their implications. Automatic repetitions not only reduce the value of the knowledge. They also make the work with SuperMemo monotonous, and are less engaging for memory. In consequence, the repeated items are more difficult to recall. A truly successful SuperMemo learner finds a challenge in each repetition.