Keeping a private "playground" code repository that hosts various "trivial"/useless projects you've flash through in your brain during free time. For most of us

Keeping a private "playground" code repository that hosts various "trivial"/useless projects you've flash through in your brain during free time. For most of us, a simple application prototype is good enough. Keep them buried for some period (maybe a month or so), then review back your code and see what's the good, bad & ugly you used to have (e.g algorithm usage, memory allocation, code style, correctness). I love this kind of "writer's retrospection" to see how much we've grown.