You can draw a box around the design activity. You can restrict the scope. Ask the designer to just focus on wireframes. Maybe you think, if we focus on creating an intuitive, attractive design, then everything will be fine.

But experiences can fail even if the visual design is perfect. For example, the person sitting on the bus can’t fill out your form because there isn’t room for their elbows. Or, they need their partner there to make a decision, but their partner isn’t there. Or, they're still waiting for the page to load.

Because we’re committed to the success of the whole product, we make and test hypotheses with designs that push into the areas adjacent to the product in the life and the mind of the user. This can take more than just generating an intuitive design from a spec. But it’s worth it. And it’s the Lab Zero way.