The best model by Hugh Dubberly! It has been helping me intentionally practice "thinking outside the box" the mindset
The designer thinking day 1 model. Ya I hear sometimes it could be "too theoretical", but at least it let us know where we are making a leap of faith while we have to.
What are all the stakeholders, what do they do, and how are their actions related to each other. Layer by layer, step by step. Great for service design.