Achieving data saturation in qualitative interview research is not mandatory in all cases. Still, it is widely considered a best practice and a key indicator of rigour in qualitative research. It depends on the research goals, design, and epistemological approach. In approaches like grounded theory or thematic analysis, data saturation is often considered essential because the goal is to develop a rich, detailed understanding of a phenomenon. Saturation ensures that the findings are robust and well-supported. In exploratory studies, where the aim is to uncover new insights or theories, saturation is crucial to capture all relevant perspectives. In some studies, the sample size is determined in advance due to practical constraints (e.g., time, funding, or access to participants). In such cases, saturation may not be achieved, but the research can still provide valuable insights. If the goal is to describe a specific context or phenomenon rather than generalize findings, saturation may be less critical. The focus is on depth rather than breadth. In case study research, the focus is on a specific or small number of cases. Saturation may not be applicable if the goal is to provide an in-depth analysis of a unique situation.

Not necessarily, unless you are aiming for a grounded theory study.