The length of time it takes to paint a portrait can vary greatly even between two portraits of similar size, composition and background. The simple answer is that it takes many hours of sketching, painting, analyzing, and more painting, to keep the portrait moving towards completion and that for each portrait the time spent at each stage can be wildly different.

Elizabeth Whelan has found that instead of counting hours she simply starts the process and aims for a level of excellence and completion that she will recognize when she sees it, and at that point the painting is finished.

Although it is possible to work diligently towards, for example, an unveiling on a particular date, unlike her illustration work it is not possible to cut corners and work in a different style in order to make a very short deadline. For this reason she, like the majority of portrait artists, gives a wide window of 2 to 6 months to complete a painting based on the size and complexity of the portrait and other commissions scheduled.