Evaluative judgement is the ability to understand what constitutes the quality of a performance or product and to apply this understanding in the evaluation of one's own or another's task. It is, therefore, a key element in the development of learning to learn competences linked to professionalism. Experiences that explicitly encourage it in university studies are therefore essential. Peer feedback strategies could be one way of developing it. This paper presents the results of an intervention, based on a didactic sequence that included a peer assessment process, carried out in three courses with an iterative task of two feedback loops. A total of 1173 comments from 114 students were collected and analysed under a triple categorisation. A classification of peer comments is presented, which can be used and transferred to other work aiming at a similar analysis. From the first loop to the second, a higher percentage of comments classified as positive corrective feedback is observed, and an improvement in the quality of comments in all courses. In addition, the quality of comments differs greatly according to the type of assessment criteria. These results are discussed, outlining strategies for future designs.