The emphasis on Continuing Professional Development (CPD) for school leaders has changed recently. Internationally, there are tendencies towards the use of multiple learning approaches and formats in a variety of modes and settings (x). Although self-reflection has had a central place in professional learning since the foundational work of Dewey (1933), few CPD programs use diagnostic evidence-based, self-assessment data and a group coaching model as an entry point to sustainable professional learning. Such an approach has been discussed in the previous papers. Important aspects, which are emphasised in this approach, are personal and professional needs, demands, practice, action, application and sustainability orientation. Using qualitative and quantitative research approaches, the triangulation of data, across countries, shows that professional self-reflection may be stimulated by using a feedback inventory and group-coaching. It shows that participants using this approach are highly stimulated to reflect on their professional competences and their work environments. Besides, the triangulation of data demonstrates that increased (quantitatively) and intensified (qualitatively) reflection increases the self-awareness and sensitivity of general and situational behaviour, particularly in critical circumstances. This approach to CPD contributes to the literature on educational leadership and potentially has application to other professional contexts.