One crucial part of education is teaching students to critically evaluate and reflect on their work. One way to perform this is through peer review and self-assessment. In this research paper, we present the results of a longitudinal study over five years with 239 students following the implementation and evaluation of peer review and self-assessment. Using qualitative and quantitative analysis, we explore different types of self-assessment, the benefits of incorporating self-assessment into the learning process, and lessons learnt during the years. Results show that students appreciate assessing their own and others' work. The students in the study are very good at evaluating their capabilities, the difference between the self-assessment and teachers' final assessment was about 10%. With a studio-based approach, with formative feedback throughout the process, individual oral and written presentations and support from self-assessment, team feedback and teacher discussions, there is a much higher certainty that students are assessed accurately.