The idea is you draw the same thing over and over again, changing one detail at a time. By the end, not only have you figure out the "right" way to draw that image, you've also got some interesting alternatives that might not be right for this drawing but could be useful in the future. This is something that I've always sort of done intuitively when designing a character, but as this video explains, there is a way to take a more analytical and productive approach.
One problem I had with the "Stray Cat" story was that the character of the hobo was changing too much from page to page. I was really happy with how I drew him on the first page and basically just traced that image when I could get away with it on later pages.
As you can see, my first two attempts to draw the character looked nothing like the version I was happy with on the first page. So for the third take, I traced the original. Still a lot of room for improvement.
Curious about this concept of iterative drawing, I decided to draw the hobo over and over again, using the first drawing as a base. Even though I still like the original the best, I did stumble upon some interesting options to file away for later.
While I don't think first head in the second row works for the tone I wanted for this story, I still really like the way it looks. I also think the beanies in rows two and four work more simply than the hatching I was doing before. I kind of like the ears sticking out in row three, but it doesn't make sense for how cold it is in the story. I could draw an infinite number of variations, but since I already had a clear mental image of the character, most of the changes I did didn't look better, just different. As Sycra's video explains (seriously, watch it) you can use this approach not just for faces or anatomy, but also for finding intersting landscapes, layouts, action, etc... really anything.
Hope somebody out there finds this useful!