An underappreciated reason people pad estimates is that it gives them some time to breath and know what business goals they personally need to deliver. In the

An underappreciated reason people pad estimates is that it gives them some time to breath and know what business goals they personally need to deliver. In the case of 1 day to add a button, let the developer have a day of knowing "today, my goal is to add a button". Without the padding the developer would be thinking "I'll add that button, but after that I have no idea what's coming, whatever bullshit comes down the pipe I guess". It's really hard to shift mental gears. People can do multiple tasks well, but only if there is a coherent thread they can follow through those tasks. Current software management philosophies are very hostile to those coherent threads.