We can reopen closed questions per reopen votes or moderator decision. But most closed questions just stay closed. They pollute search results and hurt the reputation of the askers. See also: The Stack Overflow Question Lifecycle
While some of these questions may still have useful answers, most have no answers and no upvotes.
I have asked moderators from other SE sites how long we should wait until we delete those questions. They said three days. This seemed too short … so I took three weeks and went for a big clean-up. Now there a re no closed questions without answers and upvotes that were closed before 2. June.
Very, very few questions are reopened at all. I closely monitored this, and judging by what I have seen the three days seem to be indeed the window of action. I haven’t seen one question that was reopened after a longer time period.
But before we narrow down the deadline: I think this is a case where we need to set our own rule. We as in community, not just moderators.
How long should we wait?
And what should we do with closed questions with answers or upvotes?
I am asking for answers by users which are not moderators. We cannot and we should not decide that without the community.
I will go down to two weeks now. Raise your objections in our lovely answer field.