Increasingly, we are seeing question askers wait only a matter of hours before accepting an answer. My understanding is that it would be far preferable to wait at least a couple of days before doing so, as this gives others the opportunity to give what might be much better answers.
How can we encourage this behaviour more overtly?
It is completely and utterly up to the person who asks the question whether they wait or not the accept an answer. They get to pick, it is entirely their opinion.
However, when someone does accept an answer quickly on a question that is fairly subjective I'll often post a version of the following comment:
Hello, just so you know, it's generally considered good manners to wait about a day before you accept an answer. This is actually very much for your own benefit. We have a bunch of great users who post really great answers, they live in different time zones and often take several hours to respond. When you accept an answer you discourage these folks from contributing potentially better answers, so we advise you to wait about a day before you click the check mark.
This works exceptionally well if the person whose answer has been accepted posts it. It let's the OP know that you have their best interests in mind and that you're not being self serving by asking them to wait.
I think that for questions that are about rules, where there is a single, objectively correct answer the user can accept it if it is detailed enough for them. This is because the only alternate answers are going to be either repetitions of the existing answer, or wrong answers.
However, more experienced users will still tend to wait so that they have the best possible selection. This is good, but not always necessary. Some questions have the potential to be answered quickly and accurately, but could also receive a more in-depth answer with suggestions on how to avoid a problem, alternative courses of action, or more rules quotes/links.
For more subjective questions I think it should be discouraged to accept an answer for at least 24 hours, to allow all time zones to attempt a response. I think that @waxeagle's method of simply commenting to let the user know is effective - I have seen it used successfully many times.
Overall, we should let new users accept answers for simple questions without waiting long, as they are likely to want a quick and simple solution. More experienced askers, or longer questions, should be encouraged to wait by simply leaving a message for them.
I think that if someone finds an answer sufficient then it shouldn't matter about the time frame. At the end of the day, as far as they are concerned they are satisfied and though there may be someone currently typing an extrapolated version of the answer with better referencing; if the question is answered, is there a need for it? Maybe, but that's for the individual to decide.
They can of course still keep track of the question and alter their accepted answer but it would be bad form for people to comment on how quickly it was accepted.
Hells, only today have I noticed a slight influx of questions and loads of answered icons, which is nothing compared to the melee that is Stack Overflow!
Edit: to reference the Help pages on:
What does it mean when an answer is "accepted"?
Accepting an answer is not meant to be a definitive and final statement indicating that the question has now been answered perfectly. It simply means that the author received an answer that worked for him or her personally, but not every user comes back to accept an answer, and of those who do, they may not change the accepted answer if a newer, better answer comes along later.
I would be nice if you did not answer your own question without waiting for other to get a chance to answer first.
Edited as comments to answer tend to be deleted:
But it seams "it is not merely OK to ask and answer your own question, it is explicitly encouraged" by Jeff Atwood. You are allowed to give duplicated answer but you risk being down voted if you don't significantly improve on the answer.
