You will never receive explicit instructions in a program specification about how to design a project. We will never say there should be some minimum number of constants or some minimum number of functions, since individual programmers will naturally come up with different designs for the same project.
There are techniques for design, which we have been covering in the lectures (use of constants, top-down design, writing general functions, etc.), that every good programmer uses. We expect you to use these techniques and not just write something that works. Design will always count for 25% of your project grade, since it is one of the most important aspects of programming.