If you don’t drive enough miles to change your oil by mileage, then I would recommend twice per year, once at the beginning of winter, and once at the end of winter. Winter is particularly hard on engines and oil, since people tend to drive more, drive shorter distances, idle a lot, and may rarely get the engine to operating temperature for extended periods. Cold starts are the worst, cold idling is nearly as bad. So, starting winter with good oil is important, then change the oil at the end of winter to get all the sludge and buildup out.
Of course, as others have mentioned, follow whatever your manual tells you, I expect it is 7500 miles or 6 months. If it says once per year, I would change the oil right at the beginning of winter, for reasons stated above…but they won’t void your warranty if you change the oil more often than the recommended minimum.
Last bit, always change the oil hot, so it evaporates all the water, and picks up all the sludge so it will drain out. A good 30 minute drive at a minimum, a full hour is better, before an oil change. Do this and you should never need to "flush" your engine.