"Generate and cull" is good process not just for design, but for life in general. Iterate, iterate, iterate! Each time you work through a problem, you're going to learn something new in the process. So, when working with our icons, producing a lot of versions in a short amount of time allows us to assess what is working and what is not, and make improved iterations from the best qualities. While culling, we might even decide that certain icons are not working at all, and weed them out to help improve the set as a whole.