most modern fuel injection cars have a sealed fuel system, the tank is not vented therefore the aromatics in fuel can not escape. Most boat and carbureted systems are vented to the atmosphere and the fuel will degrade in as short a time as six months depending on the the storage conditions and vent size.
The alcohol in modern fuel is the first to go and causes bad corrosion in the process. I personally highly recommend stabil or similar and or draining the carb on anything that is going to sit more than six months.
I have lost count of the carbs I have had to remove and clean for friends