My first touch to study Customer Centered Service Design was 2 days Design Thinking class. I have a background in Human Computer Interaction design and Usability testing so I had rough idea what the design thinking could be even though I completely lack the Service background.
For me user centered design process has always roughly been 1) understand users and their needs by whatever means available, 2) innovate based on user data and 3) refine and prototype the idea and test with real end users… Iterate. Preferably with multi-talented team containing both design and technical experts. But I typically work on phase where the general concept idea has been decided and at least on some level requirement brief exists and it has the initial support from business already. So my work has mostly been refining and enhancing the idea, implement it via wireframes and visuals and test it with end user.
Service Design Thinking theories and models give more systematic process, more granularity into design project phases and they include more management/business thinking into the process as well. There are different models that more or less introduce similar thinking with slightly different words and slightly different perspective: IDEAO’s 3I, IDEAO’s HCD, Model of the Hasso-Plattner institute, Double Diamond, SDT and Evolution 6^2 (Tschimmel 2012, Mindshake 2016) ). The impression I got was that the best model is the one that resonates best with you and your project. All the models carry the same thought that in the design process there is/are Divergent phase(s) and Convergent phase(s), that first you need to broaden your thinking through systematic research with user and some point you start to need to evaluate, filter and refine ideas towards solid concept.
Evolution 6^2 is model that brings most granularity into the process. It divides the process to 6 phases: Emergence, Empathy, Experimentation, Elaboration, Exposition and Extension. ^2 reflect that in each phase has divergent and convergent phase (Mindshake 2016).