I have only asked three questions but on those even after I have "accepted" an answer I still receive notifications of new answers.
In all cases the answers given after I have accepted one of those available after my "waiting period" (about a week) have genuinely added little or nothing to the topic. I am particularly fussy because I try to state why it is I have accepted an answer. If an answer of such amazing depth and insight were to be added that it blew the current best out of the water I would change where the tick got placed and say why.
I think people might view the green tick as a "done deal" and move on. I have to say that doesn't match up to my experience where I read every answer on a question I'm interested in and upvote those answers I feel are adding something new or of significant value.
On a Q where than can be a right A obviously there is little point coming late to the party. However, in Writers.SE there is only best and a new best could happen at any time.
But that's just the way I view it.