Day after the conference deadline: goofing off.
Day after the day after the conference deadline: cleaning up. Taking stock of all the urgent tasks that got shoved aside to make room for the conference submission, apologizing for things that were not done and people who were ignored, and working at getting things back under control.
Almost every computer scientist I know works in that way. Almost none of the mathematicians or physicists I know work in that way. Why have we chosen such a stressful and unpleasant way of organizing our work? More importantly, why is it so hard to break the habit? Part of the reason is that the minority rules in that case: in a group of collaborators, it is enough that one person works in that mode to force all participants to adopt it. In the DAG of tasks that need to be done, as long as a few critical tasks belong to a person of that culture, all members of the project have to also follow the same pattern of behavior, I think.
So what can be done to change behavior? Getting rid of hard deadlines would change the way the field works. One possible direction is the possibility of rolling deadlines.