The main purpose is to enhance my own creativity, eagerness to build something from thin air, for my own. There is a lot of books and articles about teamwork (a.k.a. how to make something that other people want), but there is small quantity of book about how to work alone.
Please note that these solutions are probably not the best / pythonic / well tested piece of code - its more about - how to start with something imperfect, live with it and make it better, step by step.
Most excercises have strict timeframe - 45 minutes