How long does it take a professional Illustrator to finish art?

Depends on the drawing. A professional could probably do: Sketch 5 minutes or less Simple linart: 15-25 mintues Complex linart: 1-2 hours Simple Finished Pencil Drawing: 4-8 hours Complex Finished Pencil Drawing: 10-15 hours No if you use a different medium then pencil the time changes, I'm not perfectly keen on paintings, because they vary in size and some require that the paints dry before continuing which changes the amount of time the work could take (not that most artist do the art all in one sitting, most take breaks.) Digital art is all I know mainly. Simple Finished Colored Peice: 15-20 hours Complex Finished Colored Peice: 20-45 hours (30 being a sort of 'average' it seems from the research I've done.) An artist could take considerably longer than 45 hours on work, there are outliers of 60 or 70 hours, but generally I've found the a real professional will only take about 30 hours per complex peice on average. These time rames are from my own personal experience with drawing and my reaserch on other artist, both traditional and digital.(Exstensive >.<)

it honestly depends on the size, style, medium, and how detailed the picture is. a professional should know themselves best and how long it will take them to produce new pieces of art for a client... working in pencil crayons and normally on A2 paper, basic pictures of characters without a background (like my avatar) will take me around or just over a week. with a fully detailed background it will take me just over 2 weeks. my older sister paints, and usually takes half the time i take because her medium (when needed) can take up alot of space and save time.