The only way to ascertain user expectations is to do user testing. No amount of study and debate will substitute. Efficiency of the user Look at the user's productivity, not the computer's. Keep the user occupied. Write help messages tightly and make them responsive to the problem.
Explorable Interfaces Give users well-marked roads and landmarks.
Sometimes, however, you have to provide deep ruts. Always allow a way out. Make it easier to stay in. The time to acquire a target is a function of the distance to and size of the target. Use the pinning actions of the sides, bottom, top, and corners of your display.