Complexity and People
Problem-solving is not a straightforward process. It cannot be made into a "sausage machine" where you put in the ingredients, turn the handle and out pops a solution. We do not even believe in trying to make it like this, and distrust approaches to problem-solving which imply that is can be. There are two main reasons for this view.
First, people see problems from their own particular viewpoints. More importantly, they also define (probably unconsciously) what they accept as a legitimate "space" in which solutions may be found. For example, some people are relaxed about solutions which emerge in an intuitive way. Others will only accept solutions which are developed through logic and rationality. This is a result not just of experience or training, but of their mental model of how the world can be explained and actions justified.
A perspective that helps us understand one way in which people demonstrate their preferences for problem-solving methods and types of solutions is Kirton's Adaption - Innovation Inventory. The KAI is a well-founded form of psychometric measure of creative style. (Note that this is not the same thing as measuring how creative someone is.)
The second reason for avoiding a "formula" approach to problem-solving is connected with the nature of the issue or situation that is viewed as being problematic. Put simply, "not all problems are equally difficult". A model that we have found to be particularly useful when considering the diverse nature of problems, is Snowden's Cynefin framework of sense-making in complexity.