Never worked in a proper start up, but I've given a hand several times. Usually it starts with textbook code. And that lasts around a month, month and a half. A

Never worked in a proper start up, but I've given a hand several times. Usually it starts with textbook code. And that lasts around a month, month and a half. After that deadlines start knocking on the door, as well as patches over patches to cover up things that were either not required in the beginning or extreme edge cases and it's a race to the bottom from that point on, as far as code quality is concerned.