I didn't mean the entire image would be in focus, just that your subject would be clear. A faster aperture will let in more light, so you will not need as long

I didn't mean the entire image would be in focus, just that your subject would be clear. A faster aperture will let in more light, so you will not need as long an exposure to get the same amount of detail. It can make a meaningful difference in low light shots. Adjust your aperture to get the appropriate amount of bokeh, of course; but generally I prefer as wide an aperture as possible in most situations, as long as the focus is appropriate.