This only works if you are committed to trying out the idea and then JUNKING YOUR CRAP CODE. By the nature of coding problems, the bigger the codebase gets the

This only works if you are committed to trying out the idea and then JUNKING YOUR CRAP CODE. By the nature of coding problems, the bigger the codebase gets the worse bad decisions fester, so if you approach the early rounds as "trial and error time" and then commit to a big refactor once you DO plan out the bulk of the project, this can work. Otherwise it is easy to end up with a patchy mess.