Anyone who creates knows the value of letting their work sit and ferment. It's a crucial part of the design process whether you're a designer, artist or a writer.
I like to do a quick first draft, pin it on the wall and let it haunt me for a bit. Sometimes this process is only for a day or two, but the longer, the better.
It's in the subsequent process of re-working, refining and polishing that you hit your seam of gold.
Some people say if it's really good, you should put it away for a month.