In the age of speed and instant gratification, time is an enemy. We want things now. We don't want to wait. We want results. And so, for time-pressed bakers, we have products like yeast that can speed things up.
I often time this process to bake on Saturday morning, but I had a compost meeting at the garden (no joke!) so I decided to bake Friday night instead. And since the loaves were made purely with sourdough, they tend to improve with a bit of aging and were scrumptious for breakfast the next day. Sourdough loaves will also last a week without going stale -- one of the qualities of working with natural yeast.