Been reading the Basecamp SHAPE UP site in bits and pieces.
I love this section:
Wireframes are too concrete
When design leaders go straight to wireframes or high-fidelity mockups, they define too much detail too early. This leaves designers no room for creativity. One friend put it this way:
I’ll give a wireframe to my designer, and then I’m saying to her: “I know you’re looking at this, but that’s not what I want you to design. I want you to re-think it!” It’s hard to do that when you’re giving them this concrete thing.
Over-specifying the design also leads to estimation errors. Counterintuitive as it may seem, the more specific the work is, the harder it can be to estimate. That’s because making the interface just so can require solving hidden complexities and implementation details that weren’t visible in the mockup. When the scope isn’t variable, the team can’t reconsider a design decision that is turning out to cost more than it’s worth.