I would add that not immediately accepting an answer could be done intentionally.
It is true that in the case of users with few, or zero, experience in Stack Exchange sites don't understand what accepting an answer means, but in my case, I wait accepting answers to let other users partecipate in the question. It is true that some of the questions I asked were asked during the private beta, and in that phase there are less users than during the public beta; still, I think that waiting some days before accepting an answer doesn't hurt.

I find that accepting an answer too quickly could have a negative effect on the site, especially if the accepted answer is never changed, even if a more detailed, or better answer is later written.

I would add that not immediately accepting an answer could be done intentionally.
It is true that users with few, or zero, experience in Stack Exchange sites don't understand what accepting an answer means, but in my case, I wait accepting answers to let other users partecipate in the question. It is true that some of the questions I asked were asked during the private beta, and in that phase there are less users than during the public beta; still, I think that waiting some days before accepting an answer doesn't hurt.

I find that accepting an answer too quickly could have a negative effect on the site, especially if the accepted answer is never changed, even if a more detailed, or better answer is later written.