The time taken to complete a job varies widely depending on the size of the job, the deadline and, to a lesser extent, the budget. It is quite common for me to receive a call from a magazine art director on Tuesday requiring artwork by Thursday. It’s not ideal, but certainly do-able, as long as there are no problems at the rough sketch stage. Otherwise, I would love to have a week or two to complete editorial / advertising work. Book illustrations tend to take longer as the projects are generally more involved.