Executive dysfunction notwithstanding, I always find myself doing everything from scratch specifically within the jam time limits, but I'm getting more and more curious about 'the other side' each time. So to ask a few questions about how you keep your grass so green over there....

Do you start with base code? How much base code is too much: menu systems and options are fine, but character controllers are off limits? Or does anything go: you get the entire modular platformer or whatever system running, then just fill in the lore, art/level design, and code tweaking when the theme drops? Do you think starting with base code limits your ability to innovate or makes it difficult to change your character controller(s) once the jam's started?

If you start with base code, do you always decide a genre beforehand to start working on your base code? How close to the jam do you work on it, or do you start with the same base code every time?

At the end of the day, do you think starting with base code improves your results by the end of the jam/compo, or at least improves how long you have available for polish/art/music?