Even the sharpest knife gets dull over time—the more you cook, the duller your most important tool becomes. It's only through regular maintenance that chefs and home cooks keep their blades sharp.
So how often should sharpen your knives? Well, the short answer is whenever they start to feel dull—which can vary depending on the quality of your knives and how often you use them. For most home cooks, this will likely be two to three times a year. Can your knife cut a tomato cleanly? If not, it's time to sharpen it. You can also use the paper test: Hold a sheet of printer paper up in one hand and try to slice it vertically. If you have trouble hacking through the paper, your knife could stand to be sharper.