Please don't take offense, but that's a very programmer-like approach to usability. Usability is so much more about mental models than it is about efficiency,

Please don't take offense, but that's a very programmer-like approach to usability. Usability is so much more about mental models than it is about efficiency, about helping the user feel confident & safe, than about a lack of surprises. Sensible hierarchy and visual relationships are a big thing that most people seem to forget. Workflow, too, is critical. I've used a lot of software where every screen is mathematically, scientifically "usable" but the software overall was crummy because it duplicated a workflow from another piece of software which had got it wrong initially. For example: 100% of email clients. Feed readers. Project management tools. They're all the same. Surprises are actually very good in many cases. Even "ease of use" is something you don't actually always want. My interfaces break all sorts of rules like "use standard widgets" and "conform to expectations" and "no surprises" -- but that surprise then results in an "AHA!", great enjoyment and power, and that's why people write love letters to our customer support account.