Background: There is a paucity of research on the effects of interactive feedback methods and sustained assessment strategies in formative assessment of students in the workplace. Aims: To investigate the outcome of long-term use of an assessment tool. Methods: Retrospective analysis of summarised assessment tools from 3 years of 464 final-year students in general practice. Quantitative data were analysed using non-parametric tests and a multi-level approach. Qualitative data were subjected to content analysis. Results: Students' main deficiencies in the consultation were in the domains of working diagnoses and management plans; however, supervisors emphasised goals of patient-centred communication and structure of the medical interview. As a group, students underestimated their clinical performance, compared to supervisors' judgement. Most students were supplied with specific goals, 58% with specific follow-up feedback. The majority of students and supervisors were satisfied with the assessment strategy. Long-term experience with the tool significantly increased the proportion of specific goals and feedback to students, supervisors' stringency of the assessment, and their satisfaction with the tool. Conclusions: The summarised assessment strategy proved feasible and acceptable with students and supervisors in a continuous attachment with assigned personal supervisors. However, there was room for improvement in supervisors' provision of specific follow-up feedback.