one of those moments where i think: that's kind of sketchy, and kind of brilliant

I was talking this evening to someone who works as a graduate student in one of the natural sciences. He was working on writing a review of a manuscript that the professor who runs his lab was asked to review. The idea is that the professor will briefly read over the article and the review, make any modifications that seem worthwhile, and then dispatch with his review responsibility by sending it off. The student seemed to think it was all a useful pedagogical exercise, in addition to just so happening to save his advisor the better part of a day's work. Is this common in the natural sciences? Has anyone heard of someone doing this in the social sciences?