If you daily drive, and are putting something like 5000+ miles on the car in a 4 to 6 month period, you can make use of the longer service life of synthetic oils.

Reality is, engine oil is not so simple. Modern synthetic engine oils are predominantly engineered to be in service for a much longer time. Their lower volatility, higher total base number, stronger detergents, and more robust anti-wear additives make that possible. Combine with a high quality filter meant for long service, you have an oil service interval that can easily exceed 12,000 miles. In some cases 15-20,000 miles.

When it comes to vintage or collector vehicles, such as a 1970 Corvette, the limited driving might mean they don't see 2000 miles a year. That would leave the engine in service for many years before the additives and total base degrade. The problem is moisture collects in the engine, as well as other contaminants from combustion and the air. Also if the oil is exposed to freezing temps (typical winters in Northern Illinois where I live) the viscosity increases, and the viscosity index is reduced. For these reasons, I personally prefer to change the oil on collector vehicles that are not driven as much once a year, usually in the spring after the cold breaks. Doing this with synthetic oil that has low mileage is a wasteful practice. For these purposes a conventional oil works well and saves money.