For myself by writing prototypic code correctly with pen; not only does it keep my vision straight, it also gives myself clarity and a sense of sanity of say, w

For myself by writing prototypic code correctly with pen; not only does it keep my vision straight, it also gives myself clarity and a sense of sanity of say, what that function does. With the hard evidence you can then refer back to. So, when you are ready to expand your design you already have the foundation on page. It acts as a pillar to the psuedo code that comes with design later on. If that is the going to be foundation to that function, it might as well be written correctly on paper.