To support our students during their study and exam preparation we have developed a novel synoptic revision exercise using the online PeerWise system. Academic staff involvement was passive after introducing the assignment to the cohort via scaffolding activities, thus generating an entirely student-led peer-learning environment for the task. Student engagement exceeded all expectations with high levels of activity and peer-learning occurring over a wide range of topics. We report on a detailed investigation of the quality of the student-generated content, involving two years of data with separate cohorts. The analysis includes classification of the student question type (revised Bloom's taxonomy), investigation of the utility of the feedback/model answers, along with time-resolved analysis of activity during the coursework window. The research seeks to reveal the nature of student behaviour in a peer-review environment and alleviate some of the common concerns held by academics considering moving to this type of activity.