In my case it takes me less than one hour. But then again, it depends on how much research is necessary in order for it to be factual and accurate. But even with a lot of extensive research I get it done rather quickly. I am not sure why; I guess when the germ of creativity is there, I'm fired up ready to go and the work seems to come effortlessly.
So I would have to say an hour or less. :)
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