Rather, they continually re-visit the various stages as they gain additional knowledge. In your projects, for example, you may define a problem by determining that your client needs a new kind of web page. Then you may gather information from the students and faculty who will use the page and sketch some alternative pages that you think will accomplish your client's and users' needs. However, once you show these sketches to your users, you may find that they actually want something quite different from what they first described to you and from what they were originally able to imagine. So you go back to your client with this information, and may end up re-defining the problem and designing a radically different web design or maybe even a brochure instead of a web page.
Designers always stop before they've reached perfection.
Part of the process is getting the product out the door. Conceptual design vs. detailed design. To do detailed design, you'll need a more advanced knowledge of math, physics, and computers and you will have acquired expertise in a specific engineering discipline, such as chemical engineering or materials science. Well before that time, however, you can familiarize yourself with design process and develop ideas for solving problems. That way, by the time you work on a capstone project as a senior or take a job in industry, you will already know how to define problems, generate alternatives, interview clients, write reports, and give presentations.