It is axiomatic that the best designed tool, social program, widget, or information retrieval system meets the important needs of users and is adapted to how they think, feel, and act. Models of good design process in one way or another include efforts to understand users, envision products and programs based on this understanding, test design elements and models with users, and adjust designs based on user reactions.
Most models assume an iterative and interacting process.
A challenge in all good design processes is identifying which user needs and characteristics are essentially unchanging and which are not, and of the latter which should be changed. Students learn and develop. New opportunities create apparently new interests. An innovative IR system could create new needs. Some argue that the Web is just such an innovative information system.