Is it just me or is the clock in the graphic taunting you too?
I imagine most of us will answer, "it depends." For me, it depends mostly on how well the creativity is flowing more than anything. I can be working on a simple, single photo/clean design page and have it take *days* until I feel it is done. Other pages might be technically difficult but I can finish in an hour or so.
My bottom line answer: Anywhere from an hour to three days.
Is that helpful? Can you relate?