Or maybe not. I blush to admit just how little time it took to create this render of a blue marlin, yet it is the most popular image I have. At the other end of the scale is this fantastic image of Susan's. If I remember correctly, it took days to render, but with absolutely fabulous results!
Time is always something that we should consider. It takes time to set up a scene in 3D, add the lighting, position the camera just so. Then it takes even more time to render the image at the size you want to submit. So manage your time accordingly. Break up creating the scene into manageable chunks of time. Keep lots of notes!