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.