I mentioned the “adjacent possible” above. For most of us, our creativity allows us to explore not all possible outcomes, but only a small portion of what is possible, limited by our history, biases, and perspectives. This is how our brains evolved. We create memories throughout our lives and draw from those memories, or our “history”, when we need to make decisions about the future (any future, immediate or long-term). This is why we interpret data differently. We only have our own history to draw from, and everyone’s history is slightly to vastly different from each other. The more diverse a person’s history the more adjacent possibles she has to draw from, but the number of possibilities is still limited — one person’s brain can only hold so much.
In the case of a project where both desktop and mobile are in scope, and of roughly equal importance, my personal preference is to begin the design process with desktop (surprise). I find having a bigger canvas challenges me upfront to deal with greater complexity and, in turn, forces to me to think more creatively. I find the constraints of mobile hamper my thinking; from the outset I’m bound by a reductive mindset that causes me to be constantly preoccupied with what I can tuck away, remove, or find some workaround for. I’d rather start big and blue sky, not worrying about the edges of the canvas. I can easily edit and whittle my designs down, removing what isn’t necessary, but I can’t bring designs into being that I never had the space to imagine in the first place.