I must admit I do this sparingly because I have usually moved on to the next story idea etc. (I also think it is something best done sparingly anyway and for your very best ideas only, otherwise you dilute your own work too much).
This situation comes about when I realise I am having problems working out where exactly to end a story. Do I leave it at the short punchy ending which suits flash fiction so well or do I extend the characters out (and the plot with them) and trust the right ending will emerge from that (it always does incidentally)?
My main method of working out the right story ending is to work out at which point the story has the most impact on the reader and that is where I leave the tale. Nothing more, nothing less, job done. For flash fiction, which aims to give short, sharp impressions on the reader, this is by far the best way of working out where to stop the story (I think).