I have always believed that repetitive listening and reading of interesting content helps to reinforce learning of words and phrases. This is especially true if the repetitive reading and listening is combined with a systematic approach to reviewing new words and phrases as we do at The Linguist. However, the repetitive listening and reading can be overdone. A learner should move on to new content, even before the old content is fully understood. It is important to be exposed to as much new content as possible.
There several reasons for this and for making sure that the listening and reading is “extensive” enough. First of all it makes the input activity more interesting. This is key to motivation. Second, it makes sure that the learner is exposed to as much language as possible, and to many new occurrences of the words and phrases he/she is learning. Extensive listening and reading is also developing the ability of the brain to interpret and process the new language.
So repetitive listening and reading is important but should not be overdone. Nor does the learner need to fully master one bit of content before moving on to the next. Perfection or total mastery is not the short term aim of language learning, although it can be the long term aim, even if that aim is not likely to be reached!