There are lots of views but
BP considers the storage life of fuel in a sealed container to be 6 months @ 20C (3 months @ 30C).
However, when fuel is stored in equipment containers, like the tanks in lawn mowers, motorbikes and old cars, storage life is considered to be 1 month. But as modern vehicle fuel tanks are sealed... i guess storage life depends on how sealed the tank is. I'd think the truth is somewhere between 1 month and 6 months.
Some advise filling up the tank completely (as it reduces water ingress via water vapor in the air). Some advise keeping the tank at 1/3 topping up when you are goint to drive (replenises teh most volatile stuff).
Probably the biggest proviso, is that one shouldn't use petrol containing ethonol if living in humid climates when you store the vehicle for long periods. This is mainly due to ingress of water vapour causing it to mix with the ethonol which ends up with water/ethanol mis at the bottom of the tank. The process is complex and its called phase seperation. Starting a car with lots of water/ethanol at the bottom of your tank can cause damage
Other than that, fuel stabiliser is used to primarily to stop rust and such issues on older metal fuel tanks. Modern cars have plastic tanks and pipes so it's probably not needed. Oddly it's a selling point of BP ultimate which contains anti-oxidants, metal deactivators and corrosion inhibitors.
A fuel stabiliser can't stop the natural evaporation of the most volatile components (or any components for that matter) otherwise Fuel companies would be using it in their fuel as part of the standard composition (to increase storage life).
ps: fixed up speeling mistakes and clarified what equipment container is...
