If I'd go in a deep process description, it would be long.
Basically, not really. If I get the idea in mind really accurately, it might take me around 30 mins, and mostly the time is spent for little details. I try all tiles in all places just to see how they look there. If they suit there, hehe. Knowing a few tricks from other authors is neat - like, knowing some tile combos. Another thing is when check before submission - sometimes I might find that some tile shouldn't be there after some time passed. And then I start correcting that stuff and (as in one case) I might scrap everything and start again.