Software designers are facing pressure on two fronts. Companies want to shorten development schedules to introduce products quickly, while customers want higher usability. Traditional iterative usability engineering approaches are not well suited to meet both of these demands. Iterative design stretches out the design process, as one design concept follows another until the desired result is achieved. Parallel design compresses the process by having several people work on a project's initial design independently and at the same time. This generates many ideas quickly and allows subsequent development to focus on the most promising concepts. Because several designers work on several concepts simultaneously during a project's first design phase, and because many of their ideas are not subsequently used, parallel design is considerably more expensive than iterative design. However, it is preferable when time-to-market is critical.