Why is there a 15 minute time limit on accepting an answer in StackOverflow?
It's actually 15 minutes as far as I know. It started here:
The rationale is that if people are accepting answers within minutes or even seconds (no joke), they haven't even had time to properly evaluate or test the answer. The community felt (and I agreed) that some users were just accepting the first answer that was submitted even if it was wrong or sub-par.
15 minutes was decided on as the minimum amount of time it would take to receive a healthy number of submissions and actually read/test/think about the answers provided.
To allow people enough time to answer, and allow enough answers to come in for you to choose the correct one.
It was implemented in the past two months.
People felt that in order to help get rid of the fastest gun in the west problem, delaying the time until a user could accept an answer would give everyone a fair chance at answering it to the best of their ability.