Is the StackExchange model a good one for avoiding duplicate questions on community Q&A sites

1. How long does it take for a StackOverflow question to be answered?
2. What is stack exchange used for?

How long does it take for a StackOverflow question to be answered?

Although most questions on StackOverflow are answered in less than an hour, we observe that about 30% of the questions which are not answered within an hour have a response time of more than a day (see Figure 1).

What is stack exchange used for?

Stack Exchange is a network of question-and-answer (Q&A) websites on topics in diverse fields, each site covering a specific topic, where questions, answers, and users are subject to a reputation award process. The reputation system allows the sites to be self-moderating.