In a dual initial vocational education and training (IVET) system, an integration between school- and work-based learning is essential to provide apprentices with necessary trade-specific skills and to ensure the quality of training. However, apprentices often perceive a disconnection between learning sites. Accordingly, based on the concepts of boundary crossing and school-workplace connectivity, this study aimed to investigate how the integration between school- and work-based learning contributed to the quality of Swiss IVET from the perspective of apprentices, vocational teachers and in-company trainers. Data were collected through focus groups (n = 64) and thematic data analysis was carried out following an inductive and deductive approach. Key findings indicated some issues related to sociocultural differences between school and training company: a general devaluation of school-based learning (non-aligned with workplace-learning or perceived as useless) and the diversity of apprentices' experiences at the training company. Furthermore, the analysis revealed how these situations perceived as disconnected can become learning opportunities: by applying a skill acquired at school in the workplace that is not part of the routine (learning mechanism of transformation); by bringing in the classroom authentic situations experienced by apprentices at work (learning mechanism of reflection). Implications for training and teaching are addressed.