Observations of how people construct process representations have shed light on how people approach this task and why and when errors occur. One of the key findings is that certain techniques seem to be better than others, but no technique always outperforms the others. Therefore, the hypothesis will be examined that in order to get optimal results there needs to be a fit between the applied technique on the one hand and the task to be performed as well as the task performer on the other hand. This hypothesis will be examined from two viewpoints. In the domain of process modeling, a scientific method will be developed where the modeler trains and applies a technique that is optimally aligned to the assignment and to his cognitive profile. In the domain of cognitive psychology, a theory will be built that relates the fit between an applied technique and the properties of a problem solver and a task to the cognitive load posed on working memory. The proposition is that applying a fitting technique will lower the cognitive load, which results in decreased effort and increased effectiveness. Four additional contributions will result from the research. The problem solving theory will be translated to learning. Next, a differentiating learning instrument will be developed. Further, the proposed theories will be applied in the domain of text writing and programming and it will be investigated what is the best way to approach text writing or programming in a specific situation.