Short answer: no, not automatically. Annual treatment can be a sensible habit for some wooden urban outdoor furniture, but it is not a universal rule. What really matters is the wood species, the finish, how exposed the piece is, the local climate, and how heavily it is used. A teak, cedar, eucalyptus, or acacia bench in a sheltered courtyard may go a year or two between oiling. A piece in full sun, regular rain, sprinkler spray, and heavy foot traffic may need attention more often. Painted or varnished furniture is a different story: it usually needs inspection and touch-up when the coating wears, not a blind annual treatment.
In cities, wooden outdoor furniture faces more than weather. It deals with pollution, bird droppings, dust, shade that encourages mold, and constant handling. Those conditions can break down a finish faster than sun and rain alone. That is why an annual inspection is more useful than an automatic annual treatment. Clean the furniture with mild soap, water, and a soft brush, then let it dry. Avoid harsh pressure washing, which can rough up the grain and force water into joints. Check for dry, grey wood, splintering, cracks, loose joints, mold, and worn finish. A simple test: sprinkle a little water on the surface. If it beads up, the finish is still doing its job. If it soaks in quickly, the wood is thirsty.
For oiled furniture, a fresh coat every 12 to 24 months is often enough, though harsh exposure may call for yearly attention. For film-forming sealants or varnishes, treat when the coating is worn, dull, or chipping; spot touch-ups may be needed yearly in high-wear areas. Apply products in dry, mild weather, use thin coats, and wipe off excess oil so it does not become sticky or attract dirt. Do not over-oil, because too much product can trap moisture and encourage mold.
So, do you need to treat wooden urban outdoor furniture every year? No—not as a strict rule. Inspect it every year, clean it regularly, and treat it when the wood or finish tells you it needs help. That approach protects the furniture without wasting time or product.