That's an excellent question! Caring for your wooden benches is key to making them last for years. There isn't a single universal timeline, as it depends heavily on your climate, the type of wood, and the quality of the previous finish. However, a good general rule is to inspect your benches annually and plan to re-seal or re-stain them every 1 to 3 years.
Think of the finish as your bench's sunscreen and raincoat. Over time, sunlight (UV rays) breaks down the stain or sealant, and water can seep into tiny cracks. The most obvious sign it's time for a refresh is when water stops beading up on the surface and instead soaks into the wood. Look for fading color, a dry, grayish appearance, or areas that feel rough.
For a more precise schedule: In harsh, sunny, or wet climates, you might need to reapply a coat of sealant every year. In milder, covered areas, a high-quality finish could last 2-3 years. Always start with a thorough cleaning and allow the wood to dry completely before applying any new product. A little regular maintenance keeps your benches beautiful and functional season after season.